Targeting BCL11A distal regulatory elements for fetal hemoglobin reinduction

ABSTRACT

Provided herein are methods and compositions for increasing fetal hemoglobin levels in a cell by disrupting BCL11A expression at the genomic level. Also provided herein are methods and compositions relating to the treatment of hemoglobinopathies by reinduction of fetal hemoglobin levels.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. Pat. No. 9,822,355 issued on Nov. 21, 2017, which is a 35 U.S.C. 371 National Stage Application of International Application No. PCT/US2013/072236 filed on Nov. 27, 2013, which designates the United States, and which claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Application No. 61/730,323 filed Nov. 27, 2012, of U.S. Provisional Application No. 61/730,369 filed Nov. 27, 2012, of U.S. Provisional Application No. 61/776,144 filed Mar. 11, 2013, and of U.S. Provisional Application No. 61/889,174 filed Oct. 10, 2013, the contents of each of which are incorporated herein by reference in their entireties.

GOVERNMENT SUPPORT

This invention was made with government support under grant number HL032259 awarded by the National Institutes of Health. The Government has certain rights in the invention.

SEQUENCE LISTING

The instant application contains a Sequence Listing which has been submitted electronically in ASCII format and is hereby incorporated by reference in its entirety. Said ASCII copy, created on Jun. 19, 2015, is named 701039-076205-US_SL.txt and is 49,435 bytes in size.

BACKGROUND

Normal adult hemoglobin comprises four globin proteins, two of which are alpha (α) proteins and two of which are beta (β) proteins. During mammalian fetal development, particularly in humans, the fetus produces fetal hemoglobin, which comprises two gamma (γ)-globin proteins instead of the two β-globin proteins. During the neonatal period, a globin switch occurs, referred to as the “fetal switch”, at which point, erythroid precursors switch from making predominantly γ-globin to making predominantly β-globin. The developmental switch from production of predominantly fetal hemoglobin or HbF (α₂γ₂) to production of adult hemoglobin or HbA (α₂β₂) begins at about 28 to 34 weeks of gestation and continues shortly after birth until HbA becomes predominant. This switch results primarily from decreased transcription of the gamma-globin genes and increased transcription of beta-globin genes. On average, the blood of a normal adult contains less than 1% HbF, though residual HbF levels have a variance of over 20 fold in healthy adults and are genetically controlled.

Hemoglobinopathies encompass a number of anemias of genetic origin in which there is a decreased production and/or increased destruction (hemolysis) of red blood cells (RBCs). These also include genetic defects that result in the production of abnormal hemoglobins with a concomitant impaired ability to maintain oxygen concentration. Some such disorders involve the failure to produce normal β-globin in sufficient amounts, while others involve the failure to produce normal β-globin entirely. These disorders associated with the β-globin protein are referred to generally as β-hemoglobinopathies. For example, β-thalassemias result from a partial or complete defect in the expression of the β-globin gene, leading to deficient or absent HbA. Sickle cell anemia results from a point mutation in the β-globin structural gene, leading to the production of an abnormal (sickle) hemoglobin (HbS). HbS is prone to polymerization, particularly under deoxygenated conditions. HbS RBCs are more fragile than normal RBCs and undergo hemolysis more readily, leading eventually to anemia.

Recently, the search for treatment aimed at reduction of globin chain imbalance or predisposition to hemoglobin polymerization in patients with β-hemoglobinopathies has focused on the pharmacologic manipulation of fetal hemoglobin (α2γ2; HbF). The therapeutic potential of such approaches is suggested by observations of the mild phenotype of individuals with co-inheritance of both homozygous β-thalassemia and hereditary persistence of fetal hemoglobin (HPFH), as well as by those patients with homozygous β-thalassemia who synthesize no adult hemoglobin, but in whom a reduced requirement for transfusions is observed in the presence of increased concentrations of fetal hemoglobin. Furthermore, it has been observed that certain populations of adult patients with β chain abnormalities have higher than normal levels of fetal hemoglobin (HbF), and have been observed to have a milder clinical course of disease than patients with normal adult levels of HbF. For example, a group of Saudi Arabian sickle-cell anemia patients who express 20-30% HbF have only mild clinical manifestations of the disease. It is now accepted that hemoglobin disorders, such as sickle cell anemia and the β-thalassemias, are ameliorated by increased HbF production.

As mentioned earlier, the switch from fetal hemoglobin to adult hemoglobin (α2γ2; HbA) usually proceeds within six months after parturition. However, in the majority of patients with β-hemoglobinopathies, the upstream γ globin genes are intact and fully functional, so that if these genes become reactivated, functional hemoglobin synthesis could be maintained during adulthood, and thus ameliorate disease severity. Unfortunately, the in vivo molecular mechanisms underlying the globin switch are not well understood.

Evidence supporting the feasibility of reactivation of fetal hemoglobin production comes from experiments in which it was shown that peripheral blood, containing clonogenic cells, when given the appropriate combination of growth factors, produce erythroid colonies and bursts in semisolid culture. Individual cells in such colonies can accumulate fetal hemoglobin (HbF), adult hemoglobin (HbA) or a combination of both. In cultures from adult blood, nucleated red cells accumulate either HbA (F−A+) only, or a combination of HbF and HbA (F+A+). Importantly, individual colonies contain both F+ and F− cells, indicating that both types are progeny from the same circulating stem cells. Thus, during the early stages of development in culture, cells execute an option, through currently unknown mechanisms, whether or not to express HbF. The proportion of adult F+ cells developing in culture does not appear to be preprogrammed in vivo, but appears to depend on culture conditions: A shift into the combined HbF and HbA expression pathway can, for example, be achieved in vitro by high serum concentrations, due to the activity of an unidentified compound that can be absorbed on activated charcoal.

Overall, identification of molecules that play a role in the globin switch is important for the development of novel therapeutic strategies that interfere with adult hemoglobin and induce fetal hemoglobin synthesis. Such molecules would provide new targets for the development of therapeutic interventions for a variety of hemoglobinopathies in which reactivation of fetal hemoglobin synthesis would significantly ameliorate disease severity and morbidity.

SUMMARY

Provided herein are methods and compositions for increasing fetal β-globin levels in a cell by disrupting BCL11A expression at the genomic level. Also provided herein are methods and compositions relating to the treatment of hemoglobinopathies by reinduction of fetal β-globin levels.

One aspect described herein relates to a method for producing a progenitor cell having decreased BCL11A mRNA or protein expression, the method comprising contacting an isolated progenitor cell with an agent that binds the genomic DNA of the cell on chromosome 2 location 60,716,189-60,728,612 (according to UCSC Genome Browser hg 19 human genome assembly), thereby reducing the mRNA or protein expression of BCL11A.

Another aspect described herein relates to a method for producing a genetic engineered human cell having at least one genetic modification comprising contacting an isolated cell with an effective amount of a composition comprising at least a DNA-targeting endonuclease or a vector carrying the coding sequence of a DNA-targeting endonuclease whereby the DNA-targeting endonuclease cleaves the genomic DNA of the cell on chromosome 2 location 60,716,189-60,728,612 causing at least one genetic modification therein.

Also provided herein in another aspect is an isolated genetic engineered human cell having at least one genetic modification on chromosome 2 location 60,716,189-60,728,612. In one embodiment, the at least one genetic modification is a deletion in the genomic DNA at the specified location. In one embodiment, the isolated genetic engineered human cell has reduced or decreased mRNA or protein expression of BCL11A compared to a control cell that has no one genetic modification on chromosome 2 location 60,716,189-60,728,612.

Another aspect described herein relates to a use of an isolated genetic engineered human cell having at least one genetic modification on chromosome 2 location 60,716,189-60,728,612 described herein for the purpose of increasing the fetal hemoglobin levels in a mammal.

Another aspect described herein relates to a use of an isolated genetic engineered human cell having at least one genetic modification on chromosome 2 location 60,716,189-60,728,612 described herein for the treatment a hemoglobinopathy in a mammal.

Another aspect described herein relates to a use of an isolated genetic engineered human cell having at least one genetic modification on chromosome 2 location 60,716,189-60,728,612 described herein for the manufacturer of medicament for the treatment a hemoglobinopathy in a mammal whereby the fetal hemoglobin levels in a mammal is increased.

Another aspect described herein is a composition comprising isolated genetic engineered human cells having at least one genetic modification on chromosome 2 location 60,716,189-60,728,612. In one embodiment, the composition further comprises a pharmaceutically acceptable carrier.

Another aspect described herein relates to a use of a composition comprising isolated genetic engineered human cells having at least one genetic modification on chromosome 2 location 60,716,189-60,728,612 for the purpose of increasing the fetal hemoglobin levels in a mammal.

Another aspect described herein relates to a use of a composition comprising isolated genetic engineered human cells having at least one genetic modification on chromosome 2 location 60,716,189-60,728,612 for the treatment a hemoglobinopathy in a mammal.

Another aspect described herein relates to a use of a composition comprising isolated genetic engineered human cells having at least one genetic modification on chromosome 2 location 60,716,189-60,728,612 for the manufacturer of medicament for the treatment a hemoglobinopathy in a mammal whereby the fetal hemoglobin levels in a mammal is increased.

Another aspect described herein is a composition comprising at least a DNA-targeting endonuclease or a vector carrying the coding sequence of a DNA-targeting endonuclease whereby the DNA-targeting endonuclease cleaves the genomic DNA of a human cell on chromosome 2 location 60,716,189-60,728,612 causing at least one genetic modification therein. In one embodiment, the composition further comprises a pharmaceutically acceptable carrier.

Another aspect described herein relates to a use of a composition comprising at least a DNA-targeting endonuclease or a vector carrying the coding sequence of a DNA-targeting endonuclease whereby the DNA-targeting endonuclease cleaves the genomic DNA of a human cell on chromosome 2 location 60,716,189-60,728,612 causing at least one genetic modification therein for the purpose of increasing the fetal hemoglobin levels in a mammal.

Another aspect described herein relates to a use of a composition comprising at least a DNA-targeting endonuclease or a vector carrying the coding sequence of a DNA-targeting endonuclease whereby the DNA-targeting endonuclease cleaves the genomic DNA of a human cell on chromosome 2 location 60,716,189-60,728,612 causing at least one genetic modification therein for the treatment a hemoglobinopathy in a mammal.

Another aspect described herein relates to a use of a composition comprising at least a DNA-targeting endonuclease or a vector carrying the coding sequence of a DNA-targeting endonuclease whereby the DNA-targeting endonuclease cleaves the genomic DNA of a human cell on chromosome 2 location 60,716,189-60,728,612 causing at least one genetic modification therein for the manufacturer of medicament for the treatment a hemoglobinopathy in a mammal whereby the fetal hemoglobin levels in a mammal is increased.

In one embodiment, provided herein is a use of an agent that binds the genomic DNA of the cell on chromosome 2 location 60,716,189-60,728,612 (according to UCSC Genome Browser hg 19 human genome assembly) for increasing the fetal hemoglobin in a mammal or for the treatment of a hemoglobinopathy in the mammal or for reducing the mRNA or expression of BCL11A, wherein the mRNA or protein expression of BCL11A is reduced.

In one embodiment, provided herein is a use of an effective amount of a composition comprising at least a DNA-targeting endonuclease or a vector carrying the coding sequence of a DNA-targeting endonuclease for increasing the fetal hemoglobin in a mammal or for the treatment of a hemoglobinopathy in the mammal or for reducing the mRNA or expression of BCL11A, wherein the DNA-targeting endonuclease cleaves the genomic DNA of the cell on chromosome 2 location 60,716,189-60,728,612 causing at least one genetic modification therein.

In one embodiment, provided herein is a use of an effective amount of a composition comprising at least a DNA-targeting enzyme or a vector carrying the coding sequence of a DNA-targeting enzyme for increasing the fetal hemoglobin in a mammal or for the treatment of a hemoglobinopathy in the mammal or for reducing the mRNA or expression of BCL11A, wherein the DNA-targeting enzyme produces at least one epigenetic modification in the genomic DNA of the cell on chromosome 2, thereby affecting the mRNA or expression of BCL11A. In one embodiment, the at least one epigenetic modification is at location 60,716,189-60,728,612. In another embodiment, the effect of the one epigenetic modification is reducing the mRNA or protein expression of BCL11A. In one embodiment, the at least one epigenetic modification in the genomic DNA of the cell on chromosome 2 indirectly or directly affects the location 60,716,189-60,728,612 of chromosome 2.

In one embodiment, provided herein is a use of any isolated cells described herein for increasing the fetal hemoglobin in a mammal or for the treatment of a hemoglobinopathy in the mammal.

In one embodiment, provided herein is a use of a composition comprising isolated genetic engineered human cells for increasing the fetal hemoglobin in a mammal or for the treatment of a hemoglobinopathy in the mammal, wherein the cells have at least one genetic modification on chromosome 2 location 60,716,189-60,728,612 (according to UCSC Genome Browser hg 19 human genome assembly) made by the process of contacting the cells with an effective amount of a composition comprising at least a DNA-targeting endonuclease or a vector carrying the coding sequence of a DNA-targeting endonuclease whereby the DNA-targeting endonuclease cleaves the genomic DNA of the cell on chromosome 2 location 60,716,189-60,728,612 (according to UCSC Genome Browser hg 19 human genome assembly) causing at least one genetic modification therein.

In one embodiment, provided herein is a use of a composition comprising isolated genetic engineered human cells for increasing the fetal hemoglobin in a mammal or for the treatment of a hemoglobinopathy in the mammal, wherein the cells have at least one epigenetic modification on chromosome 2. In one embodiment, the at least one epigenetic modification on chromosome 2 is at location 60,716,189-60,728,612 (according to UCSC Genome Browser hg 19 human genome assembly). In another embodiment, at least one epigenetic modification on chromosome 2 is made by the process of contacting the cells with an effective amount of a composition comprising at least a DNA-targeting enzyme or a vector carrying the coding sequence of a DNA-targeting enzyme whereby the DNA-targeting enzyme produces at least one epigenetic modification in the genomic DNA of the cell on chromosome 2 which affects the location 60,716,189-60,728,612 (according to UCSC Genome Browser hg 19 human genome assembly) causing therein.

In one embodiment, provided herein is a use of any isolated cells described herein or any one of the compositions described herein for the manufacture of a medicament for increasing the fetal hemoglobin in a mammal in need thereof or for the treatment of a hemoglobinopathy in a mammal.

Another aspect described herein is a method of increasing fetal hemoglobin levels in a cell, the method comprising the steps of: contacting an isolated cell with an effective amount of a composition comprising at least a DNA-targeting endonuclease or a vector carrying the coding sequence of a DNA-targeting endonuclease whereby the DNA-targeting endonuclease cleaves the genomic DNA of the cell on chromosome 2 location 60,716,189-60,728,612 causing at least one genetic modification therein, whereby fetal hemoglobin expression is increased in said cell, or its progeny, relative to the cell prior to the contacting.

Another aspect described herein is a method for increasing fetal hemoglobin levels in a mammal in need thereof, the method comprising the steps of contacting an isolated hematopoietic progenitor cell in said mammal with an effective amount of a composition comprising at least a DNA-targeting endonuclease or a vector carrying the coding sequence of a DNA-targeting endonuclease whereby the DNA-targeting endonuclease cleaves the genomic DNA of the cell on chromosome 2 location 60,716,189-60,728,612 causing at least one genetic modification therein, whereby fetal hemoglobin expression is increased in said mammal, relative to expression prior to said contacting.

Another aspect described herein is a method for increasing fetal hemoglobin levels in a mammal in need thereof, the method comprising transplanting an isolated genetic engineered human cell having at least one genetic modification on chromosome 2 location 60,716,189-60,728,612 into the mammal.

In one embodiment, this disclosure provides a method for increasing fetal hemoglobin levels in a mammal in need thereof, the method comprising the steps of providing an isolated population of hematopoietic progenitor cells or hematopoietic stem cells from the mammal in ex vivo, and contacting the population of hematopoietic progenitor or stem cells with an effective amount of a composition comprising at least a DNA-targeting endonuclease or a vector carrying the coding sequence of a DNA-targeting endonuclease whereby the DNA-targeting endonuclease cleaves the genomic DNA of the cell on chromosome 2 location 60,716,189-60,728,612 causing at least one genetic modification therein, whereby fetal hemoglobin expression is increased in the mammal, relative to expression prior to the contacting.

In one embodiment, this disclosure provides a method for increasing fetal hemoglobin levels in a mammal in need thereof, the method comprising the steps of isolating a population of hematopoietic progenitor cells or hematopoietic stem cells from the mammal, and contacting in ex vivo the population of hematopoietic progenitor or stem cells with an effective amount of a composition comprising at least a DNA-targeting endonuclease or a vector carrying the coding sequence of a DNA-targeting endonuclease whereby the DNA-targeting endonuclease cleaves the genomic DNA of the cell on chromosome 2 location 60,716,189-60,728,612 causing at least one genetic modification therein, whereby fetal hemoglobin expression is increased in the mammal, relative to expression prior to the contacting.

In one embodiment, this disclosure provides a method for increasing fetal hemoglobin levels in a mammal in need thereof, the method comprising the steps of providing isolating a population of hematopoietic progenitor cells or hematopoietic stem cells from the mammal and deleting the genomic DNA of the cells on chromosome 2 location 60,716,189-60,728,612 causing at least one genetic modification therein, whereby fetal hemoglobin expression is increased in the mammal, relative to expression prior to the contacting.

In one embodiment, this disclosure provides a method for increasing fetal hemoglobin levels in a mammal in need thereof, the method comprising the steps of isolating a population of hematopoietic progenitor cells or hematopoietic stem cells from the mammal and ex vivo deleting the genomic DNA of the cells on chromosome 2 location 60,716,189-60,728,612 causing at least one genetic modification therein, whereby fetal hemoglobin expression is increased in the mammal, relative to expression prior to the contacting.

In one embodiment, this disclosure provides a method of treatment of a hemoglobinopathy in a mammal comprising the steps of (a) providing hematopoietic progenitor cells or hematopoietic stem cells or iPSCs; (b) contacting the cells ex vivo or in vitro with an effective amount of a composition comprising at least a DNA-targeting endonuclease or a vector carrying the coding sequence of a DNA-targeting endonuclease whereby the DNA-targeting endonuclease cleaves the genomic DNA of the cell on chromosome 2 location 60,716,189-60,728,612 causing at least one genetic modification therein, whereby fetal hemoglobin expression is increased in the mammal, relative to expression prior to the contacting; and (c) administering the cells of step (b) into the mammal.

In one embodiment, this disclosure provides a method of treatment of a hemoglobinopathy in a mammal comprising the steps of (a) isolating hematopoietic progenitor cells or hematopoietic stem cells from the mammal; (b) contacting the cells ex vivo or in vitro with an effective amount of a composition comprising at least a DNA-targeting endonuclease or a vector carrying the coding sequence of a DNA-targeting endonuclease whereby the DNA-targeting endonuclease cleaves the genomic DNA of the cell on chromosome 2 location 60,716,189-60,728,612 causing at least one genetic modification therein, whereby fetal hemoglobin expression is increased in the mammal, relative to expression prior to the contacting; and (c) administering the cells of step (b) into the mammal.

In one embodiment, this disclosure provides a method of treatment of a hemoglobinopathya in a mammal comprising the steps of: (a) providing hematopoietic progenitor cells or hematopoietic stem cells or iPSCs; (b) ex vivo deleting the genomic DNA of the cells on chromosome 2 location 60,716,189-60,728,612 causing at least one genetic modification therein, whereby fetal hemoglobin expression is increased in the mammal, relative to expression prior to the contacting; and (c) administering the cells of step (b) into the mammal.

In one embodiment, this disclosure provides a method of treatment of a hemoglobinopathy in a mammal comprising the steps of (a) isolating hematopoietic progenitor cells or hematopoietic stem cells from the mammal; (b) ex vivo deleting the genomic DNA of the cells on chromosome 2 location 60,716,189-60,728,612 causing at least one genetic modification therein, whereby fetal hemoglobin expression is increased in the mammal, relative to expression prior to the contacting; and (c) administering the cells of step (b) into the mammal.

In one embodiment, this disclosure provides a method of treatment of a hemoglobinopathy in a mammal (e.g. a human) comprising introducing a composition described herein comprising isolated genetic engineered cells having at least one genetic modification on chromosome 2 location 60,716,189-60,728,612 whereby fetal hemoglobin expression is increased in the mammal.

In one embodiment, this disclosure provides a method of treatment of a hemoglobinopathy in a mammal (e.g. a human) comprising increasing fetal hemoglobin expression in the mammal by method described herein.

In one embodiment of this aspect and all other aspects described herein, the isolated cell or isolated population of cells is/are human cell(s).

In one embodiment of this aspect and all other aspects described herein, the isolated cell or isolated population of cells is/are progenitor cell(s).

In one embodiment of this aspect and all other aspects described herein, the human cell is a hematopoietic progenitor cell.

In one embodiment of this aspect and all other aspects described herein, the human cell is an induced pluripotent stem cell.

In one embodiment of this aspect and all other aspects described herein, the induced pluripotent stem cell is hematopoietic progenitor cell.

In one embodiment of this aspect and all other aspects described herein, the hematopoietic progenitor is a cell of the erythroid lineage.

In one embodiment of this aspect and all other aspects described herein, the hematopoietic progenitor cell or isolated is contacted ex vivo or in vitro or in vivo.

In one embodiment of this aspect and all other aspects described herein, the at least one genetic modification is a deletion.

In one embodiment of this aspect and all other aspects described herein, the deletion removes the entire region between chromosome 2 location 60,716,189-60,728,612 or removes a portion of the region resulting in disruption of one or more DNAse 1-hypersensitive sites (DHS).

In another embodiment of this aspect and all other aspects described herein, the deletion comprises one or more of the DNAse 1-hypersensitive sites (DHS) +62, +58, and +55 as described herein in the Examples section.

In another embodiment of this aspect and all other aspects described herein, the deletion comprises one or more of the SNP markers described in Table 2.

In another embodiment of this aspect and all other aspects described herein, the deletion comprises one or more of the fragments listed in Table 7.

In another embodiment of this aspect and all other aspects described herein, the deletion removes the entire region between chromosome 2 location 60,716,189-60,728,612 or removes a portion of the region resulting in disruption of one or more DNAse 1-hypersensitive sites (DHS). In one embodiment, as used herein, the term “portion” in the context of genomic deletion is at least 20%-80% of the specified region.

In further embodiment of any treatment method, the method comprises chemotherapy and/or radiation therapy to remove or reduced the endogenous hematopoietic progenitor or stem cells in the mammal.

In one embodiment of any method, the contacted cells having at least one genetic modification can be cryopreserved and stored until the cells are needed for administration into a mammal.

In one embodiment of any described method, the hematopoietic progenitor or stem cells or isolated cells can be substituted with an iPSCs described herein.

In one embodiment of any described method, the hematopoietic progenitor or stem cells or iPSCs or isolated cells are autologous to the mammal, meaning the cells are derived from the same mammal. In another of the embodiments of the described method, the hematopoietic progenitor or stem cells or iPSCs or isolated cells are non-autologous to the mammal, meaning the cells are not derived from the same mammal, but another mammal of the same species. For example, the mammal is a human.

In one embodiment of any treatment method, the method further comprises selecting a mammal in need of increased fetal hemoglobin expression.

In one embodiment of any treatment method, the method further comprises selecting a mammal in need of treatment of a hemoglobinopathy.

In any embodiment of any treatment method described, the hemoglobinopathy is a β-hemoglobinopathy.

In any embodiment of any treatment method described, the hemoglobinopathy is β-thalassemia.

In any embodiment of any treatment method described, the hemoglobinopathy is sickle cell anemia.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1A shows the distribution of 636 SNPs previously published to be associated with erythroid traits at P<5×10⁻⁸ with respect to promoter, exonic, intronic, 3′UTR, and intergenic sequences. For comparison, genomic distribution of these regions is displayed.

FIG. 1B is a graph plotting the cumulative distribution of the distances of the 636 erythroid trait-associated SNPs with respect to nearest erythroid enhancer. Erythroid enhancers were defined by sequences more than 2 kb from the TSSs of Refseq-annotated genes with DNase I hypersensitivity, presence of H3K4me1, either H3K27ac or H3K9ac, and absence of H3K4me3 and H3K27me3. The distance of mean±SD of 50 sets of 636 randomly permuted non-erythroid trait-associated SNPs (from GWAS database), SNPs from the Affy 6.0 genotyping array, or random SNPs were also plotted.

FIG. 2A shows ChIP followed by massively parallel sequencing performed from CD34⁺-cell-derived erythroid precursors with antibodies to H3K27me3, H3K4me3, H3K4me1, H3K27ac, GATA1, TAL1, and PolII. Nuclei isolated from erythroid precursors, fetal brain, and B- and T-lymphocytes subject to DNase I treatment with sites of cleavage determined by massively parallel sequencing. HbF-associated SNPs includes those associated with HbF level or F-cell number at P<5×10⁻⁸ and sentinel SNPs those with highest association to HbF or F-cell number in a given GWAS. Three adjacent erythroid DHS are labeled as +62, +58, and +55 based on distance in kb from BCL11A TSS.

FIG. 2B shows ChIP-qPCR of primary human erythroid precursors at BCL11A intron-2, normalized to 1% input chromatin. DHS +62, +58, and +55 from FIG. 2A shaded. Enrichment at negative control (GAPDH, OCT4) and positive control (β-globin LCR HS3 and α-globin HS-40) loci displayed for comparison.

FIG. 2C shows chromosome conformation capture performed in primary human erythroid precursors across BCL11A locus using BCL11A promoter as anchor. Interaction frequency is normalized to LCR-HBB interaction.

FIG. 3A shows Healthy anonymous donors from whom hematopoietic stem/progenitor cells were available were genotyped at rs1427407 to identify heterozygous individuals. Five donors were identified. The hematopoietic stem/progenitor cells were subject to erythroid differentiation culture. Chromatin was isolated from erythroblasts, and immunoprecipitated by GATA1 or TAL 1. ChIP DNA or input DNA was subject to a pyrosequencing reaction to quantify the relative abundance of the rs1427407 G-allele. Figure discloses SEQ ID NOS 197 and 198, respectively, in order of appearance.

FIG. 3B shows data from Healthy anonymous donors from whom hematopoietic stem/progenitor cells were available were genotyped at rs1427407, rs7606173, and rs7569946 to identify individuals heterozygous for the rs1427407-rs7606173 haplotype as well as rs7569946. Three donors were identified. Haplotyping revealed that the rs7569946 G-allele was on the same chromosome as the rs1427407 G-allele and rs7606173 C-allele in each. The hematopoietic stem/progenitor cells were subject to erythroid differentiation culture. RNA and genomic DNA were isolated, and cDNA was produced by reverse transcription. Paired gDNA and cDNA samples were subject to a pyrosequencing reaction to quantify the relative abundance of the 7569946 G-allele.

FIG. 3C shows mean HbF for rs1427407-rs7606173 haplotypes in the CSSCD cohort. The mean HbF level was 4.05% (SD 3.10) in 213 rs1427407-rs7606173 G-C individuals, 7.08% (SD 4.50) in 254 rs1427407-rs7606173 T-G/G-C heterozygotes, and 11.21% (SD 4.37) in 60 rs1427407-rs7606173 T-G individuals. The P-values correspond to one-tailed student t-tests. The haplotype frequencies in CSSCD are: TG: 24.5%, TC 0.085%, GC 42.3%, GG 33.1%.

FIGS. 4A-4C show data from a 12.4-kb fragment of BCL11A intron-2 encompassing the DHSs +62, +58 and +55 (encompassing +52.0-64.4 kb from TSS) cloned upstream of an Hsp68 minimal promoter and lacZ reporter gene flanked by H19 insulator elements. Transient transgenic murine embryos generated by nuclear injection at the one-cell stage.

FIG. 4A shows E12.5 transient transgenic embryo stained with X-gal.

FIG. 4B shows cell suspensions isolated from the peripheral blood and fetal liver of stable transgenic E12.5 embryos. Cytospins were stained with X-gal and counterstained with Nuclear Red.

FIG. 4C shows data from bone marrow erythroblasts (CD71+/Ter119+) and splenic lymphocytes (CD19+ for B-lymphocytes and CD3+ for T-lymphocytes) that were isolated and sorted from young adult stable transgenics. Cells were subject to X-gal staining or RNA isolation followed by RT-qPCR. Gene expression normalized to GAPDH, and expressed relative to T-lymphocytes, which express neither BCL11A nor lacZ.

FIGS. 5A-5C show mouse erythroleukemia (MEL) cells and pro-B lymphoid cells transfected with two pairs of TALENs each designed to generate a DSB on either end of the orthologous 10 kb BCL11A intron-2 erythroid enhancer from +50.4-+60.4 kb. Clones (called Δ50.4-60.4) were isolated with biallelic deletion of the 10-kb segment.

FIG. 5A shows RT-qPCR performed of Bcl11a with primer pairs recognizing sequences upstream, spanning, and downstream of intron-2.

FIG. 5B shows an immunoblot of Δ50.4-60.4 with anti-BCL11A.

FIG. 5C shows globin gene expression in Δ50.4-60.4 MEL clones. A common primer pair recognizes the adult β-globins β2 and β1, while independent primers recognize the embryonic β-globins εy and βH1.

FIG. 6 shows mouse zygote pronuclei injected with lacZ reporter construct. Transgenic embryos were isolated at E12.5. Embryos were genotyped by lacZ PCR. The fraction of transgenic embryos with X-gal staining of fetal liver is reported.

FIG. 7 shows one to two kb sequence fragments cloned into enhancer construct with TK minimal promoter and GFP Enhancer reporter constructs were delivered by lentiviral vectors to primary human erythroid precursors. Transfected cells were selected by puromycin resistance. Mean GFP fluorescence intensity was measured.

FIG. 8 shows data relating to chromatin profiling of mouse erythroid cells that reveals an orthologous enhancer signature at Bcl11a intron-2. Mouse tracks obtained from previously published global mouse erythroid chromatin profiling, with histone modifications and DNase-I cleavage from and GATA1 and TAL1 ChIP-seq from. Dotted rectangle bounds orthologous enhancer signature defining Δ50.4-60.4 element targeted for TALEN-mediated deletion.

FIG. 9A is a schematic of a TALEN-mediated genome engineering strategy used herein. TALENs are sequence-specific nucleases. Two pairs of TALENs were engineered to generate double strand breaks, one at Bcl11a +50.4 and the other at +60.4. Clones were isolated that had repaired the two DSBs by NHEJ with excision of the intervening 10-kb segment. Clones were screened by PCR with primers 5′, 3′, internal and spanning the 10-kb deletion.

FIG. 9B shows Southern blotting of HindIII digested genomic DNA from Δ50.4-60.4 clones corroborated that these clones had expected excision allele and lacked a non-excised allele.

FIG. 9C shows the Δ50.4-60.4 clones having biallelic BCL11A enhancer deletion produced by TALEN-mediated NHEJ in mouse erythroleukemia (MEL) cells and pro-B lymphoid cells. The histograms show PCR amplification produced using the primers 5′, 3′, internal and spanning the 10-kb deletion (see amplicons in FIG. 9A). All Δ50.4-60.4 clones were missing Del-1 and Del-2 amplification, indicating the presence of a biallelic deletion of the 10 kb BCL11A intron-2 erythroid enhancer from +50.4-+60.4 kb.

FIG. 10 shows Sanger sequencing of PCR products from Δ50.4-60.4 clones. 5′ (+50.4) and 3′ (+60.4) left and right TALEN recognition sequences with intervening spacers is shown. Some alleles showed evidence of end-joining directly from each digested spacer sequence whereas other alleles showed loss of hundreds of additional nucleotides. Only one allele each was isolated from MEL clone #1 and pro-B clone #2. Figure discloses SEQ ID NOS 199-215, top to bottom, respectively, in order of appearance.

FIG. 11A shows the genotype data obtained in 1,178 individuals from CSSCD for 38 variants within BCL11A +62, +58 or +55 DHSs. Most highly significant associations to HbF level among common (MAF>1%) SNPs (n=10) prior to (rs1427407) or following (rs7606173) conditional analysis on rs1427407. SNP coordinates chromosome 2, building19.

FIG. 11B the HbF association analyses at BCL11A. Genotype data obtained in 1,178 individuals from CSSCD for 38 variants within BCL11A +62, +58 or +55 DHSs. Sentinel SNPs are those with the highest association to HbF level or F-cell number in prior GWAS (7-12). These SNPs are shown with respect to BCL11A intron-2 with the 3 DHSs +62, +58 and +55 indicated.

DETAILED DESCRIPTION

The methods and compositions described herein relate, in part, to the discovery of a distal regulatory region upstream of the BCL11A gene that can regulate expression of the BCL11A protein. The BCL11A protein acts as a stage specific regulator of fetal hemoglobin expression by repressing γ-globin induction. Accordingly, the methods and compositions provided herein are novel methods for the regulation of γ-globin expression in eythroid cells. More specifically, these activities can be harnessed in methods for the treatment of β-hemoglobinopathies by induction of γ-globin via inhibition of the BCL11A gene product.

In one embodiment, provided herein is a method for producing an isolated progenitor cell having decreased BCL11A mRNA or protein expression, the method comprising contacting an isolated progenitor cell with an agent that binds the genomic DNA of the cell on chromosome 2 location 60,716,189-60,728,612 (according to UCSC Genome Browser hg 19 human genome assembly), thereby reducing the mRNA or protein expression of BCL11A.

In one embodiment, provided herein is a method for producing an isolated progenitor cell having decreased BCL11A mRNA or protein expression, the method comprising providing an isolated progenitor cell and contacting the isolated progenitor cell with an agent that binds the genomic DNA of the cell on chromosome 2 location 60,716,189-60,728,612 (according to UCSC Genome Browser hg 19 human genome assembly), thereby reducing the mRNA or protein expression of BCL11A.

In one embodiment, provided herein is a method for producing an isolated progenitor cell having decreased BCL11A mRNA or protein expression, the method comprising contacting an isolated progenitor cell with an agent that produces an epigenetic modification in the genomic DNA of the cell on chromosome 2 thereby reducing the mRNA or protein expression of BCL11A. In one embodiment, the epigenetic modification in the genomic DNA is at chromosome 2location 60,716,189-60,728,612 (according to UCSC Genome Browser hg 19 human genome assembly).

In one embodiment, provided herein is a method for producing an isolated progenitor cell having decreased BCL11A mRNA or protein expression, the method comprising providing an isolated progenitor cell and contacting the isolated progenitor cell with an agent that produces an epigenetic modification in the genomic DNA of the cell on chromosome 2 thereby reducing the mRNA or protein expression of BCL11A. In one embodiment, the epigenetic modification in the genomic DNA is at chromosome 2location 60,716,189-60,728,612 (according to UCSC Genome Browser hg 19 human genome assembly).

The disclosure described herein, in a preferred embodiment, does not concern a process for cloning human beings, processes for modifying the germ line genetic identity of human beings, uses of human embryos for industrial or commercial purposes or processes for modifying the genetic identity of animals which are likely to cause them suffering without any substantial medical benefit to man or animal, and also animals resulting from such processes.

One aspect described herein relates to a method for producing an isolated genetic engineered human cell having at least one genetic modification comprising contacting the cell with an effective amount of a composition comprising at least a DNA-targeting endonuclease or a vector carrying the coding sequence of a DNA-targeting endonuclease whereby the DNA-targeting endonuclease cleaves the genomic DNA of the cell on chromosome 2 location 60,716,189-60,728,612 (according to UCSC Genome Browser hg 19 human genome assembly) causing at least one genetic modification therein.

Another aspect provided herein relates to a method of increasing fetal hemoglobin levels in an isolated cell, the method comprising decreasing the BCL11A mRNA or protein expression in the cell. In one aspect, the decrease of BCL11A mRNA or protein expression is achieved by causing at least one genetic modification at the genomic DNA of the cell on chromosome 2 location 60,716,189-60,728,612 (according to UCSC Genome Browser hg 19 human genome assembly). In another aspect, the decrease of BCL11A mRNA or protein expression is achieved by causing at least one genetic modification at the genomic DNA of the cell on chromosome 2 location 60,716,189-60,728,612 that results in epigenetic modification of the genetic function at chromosome 2 location 60,716,189-60,728,612. In this aspect, the BCL11A enhancer activity located within this chromosome 2 location 60,716,189-60,728,612 is reduce. By decrease in this aspect, the enhancer activity in enhancing BCL11A mRNA or protein expression in the cell is at least 5% lower is at least 10% lower, at least 20% lower, at least 30% lower, at least 40% lower, at least 50% lower, at least 60% lower, at least 70% lower, at least 80% lower, at least 90% lower, at least 1-fold lower, at least 2-fold lower, at least 5-fold lower, at least 10 fold lower, at least 100 fold lower, at least 1000-fold lower, or more compared to a control cell that is not treated in any method disclosed herein. By decrease of the BCL11A mRNA or protein expression in the cell means that protein expression is at least 5% lower is at least 10% lower, at least 20% lower, at least 30% lower, at least 40% lower, at least 50% lower, at least 60% lower, at least 70% lower, at least 80% lower, at least 90% lower, at least 1-fold lower, at least 2-fold lower, at least 5-fold lower, at least 10 fold lower, at least 100 fold lower, at least 1000-fold lower, or more compared to a control cell that is not treated in any method disclosed herein.

Another aspect provided herein relates to a method of increasing fetal hemoglobin levels in an isolated cell, the method comprising providing an isolated human cell or progenitor cell and decreasing the BCL11A mRNA or protein expression in the cell.

Another aspect provided herein relates to a method of increasing fetal hemoglobin levels in a cell, the method comprising the steps of: contacting an isolated human cell with an effective amount of a composition comprising at least a DNA-targeting endonuclease or a vector carrying the coding sequence of a DNA-targeting endonuclease whereby the DNA-targeting endonuclease cleaves the genomic DNA of the cell on chromosome 2 location 60,716,189-60,728,612 (according to UCSC Genome Browser hg 19 human genome assembly) causing at least one genetic modification therein, whereby fetal hemoglobin expression is increased in the cell, or its progeny, relative to the cell prior to the contacting.

Another aspect provided herein relates to a method of increasing fetal hemoglobin levels in a cell, the method comprising the steps of providing an isolated human cell or progenitor cell, contacting an isolated human cell or progenitor cell with an effective amount of a composition comprising at least a DNA-targeting endonuclease or a vector carrying the coding sequence of a DNA-targeting endonuclease whereby the DNA-targeting endonuclease cleaves the genomic DNA of the cell on chromosome 2 location 60,716,189-60,728,612 (according to UCSC Genome Browser hg 19 human genome assembly) causing at least one genetic modification therein, whereby fetal hemoglobin expression is increased in the cell, or its progeny, relative to the cell prior to the contacting.

Another aspect described herein relates to a method for increasing fetal hemoglobin levels in a mammal in need thereof, the method comprising decreasing the BCL11A mRNA or protein expression in a hematopoietic progenitor cell in the mammal. In one aspect, the decrease of BCL11A mRNA or protein expression is achieved by causing at least one genetic modification at the genomic DNA of the cell on chromosome 2 location 60,716,189-60,728,612 (according to UCSC Genome Browser hg 19 human genome assembly). In another aspect, the decrease of BCL11A mRNA or protein expression is achieved by causing at least one epigenetic modification at the genomic DNA of the cell on chromosome 2. In another aspect, the decrease of BCL11A mRNA or protein expression is achieved by causing at least one epigenetic modification at the genomic DNA of the cell on chromosome 2 location 60,716,189-60,728,612.

Another aspect described herein relates to a method for increasing fetal hemoglobin levels in a mammal in need thereof, the method comprising providing an isolated human cell or progenitor cell from a mammal and decreasing the BCL11A mRNA or protein expression in the cell. In one aspect, the method further comprises selecting a mammal in need of increasing fetal hemoglobin levels therein.

Another aspect described herein relates to a method for increasing fetal hemoglobin levels in a mammal in need thereof, the method comprising the steps of contacting a hematopoietic progenitor cell in the mammal with an effective amount of a composition comprising at least a DNA-targeting endonuclease or a vector carrying the coding sequence of a DNA-targeting endonuclease whereby the DNA-targeting endonuclease cleaves the genomic DNA of the cell on chromosome 2 location 60,716,189-60,728,612 (according to UCSC Genome Browser hg 19 human genome assembly) causing at least one genetic modification therein, whereby fetal hemoglobin expression is increased in the mammal, relative to expression prior to the contacting.

Another aspect described herein relates to a method for increasing fetal hemoglobin levels in a mammal in need thereof, the method comprising the steps of providing an isolated human cell or progenitor cell or an isolated population of hematopoietic progenitor cells from a mammal contacting the human cell or progenitor cell or hematopoietic progenitor cell with an effective amount of a composition comprising at least a DNA-targeting endonuclease or a vector carrying the coding sequence of a DNA-targeting endonuclease whereby the DNA-targeting endonuclease cleaves the genomic DNA of the cell on chromosome 2 location 60,716,189-60,728,612 (according to UCSC Genome Browser hg 19 human genome assembly) causing at least one genetic modification therein, whereby fetal hemoglobin expression is increased in said mammal, relative to expression prior to the contacting.

Another aspect provided herein relates to a method for increasing fetal hemoglobin levels in a mammal in need thereof, the method comprising transplanting a genetic engineered human cell as described herein into the mammal.

In one embodiment of this aspect and all other aspects described herein, the method further comprises providing an isolated cell or an isolated progenitor cell or an isolated population of cells which can be progenitor cell or hematopoietic progenitor cell.

In one embodiment of this aspect and all other aspects described herein, the isolated cell is an isolated progenitor cell.

In one embodiment of this aspect and all other aspects described herein, the isolated progenitor cell is an isolated human cell.

In one embodiment of this aspect and all other aspects described herein, the isolated human cell is a hematopoietic progenitor cell.

In another embodiment of this aspect and all other aspects described herein, the hematopoietic cell is a cell of the erythroid lineage. Methods of isolating hematopoietic progenitor cell are well known in the art, e.g., by flow cytometric purification of CD34+ or CD133+ cells, microbeads conjugated with antibodies against CD34 or CD133, markers of hematopoietic progenitor cell. Commercial kits are also available, e.g., MACS® Technology CD34 MicroBead Kit, human, and CD34 MultiSort Kit, human, and STEMCELL™ Technology EasySep™ Mouse Hematopoietic Progenitor Cell Enrichment Kit.

In another embodiment of this aspect and all other aspects described herein, the human cell is an induced pluripotent stem cell (iPSC).

In another embodiment of this aspect and all other aspects described herein, the contacting of any cell described herein can be ex vivo or in vitro or in vivo.

In another embodiment of this aspect and all other aspects described herein, the contacting of any cell described herein comprises contacting with an agent that binds the genomic DNA of the cell on chromosome 2 and produces an epigenetic modification in the genome of the cell on chromosome 2, thereby reducing the mRNA or protein expression of BCL11A. In one embodiment, the epigenetic modification is on chromosome 2 location 60,716,189-60,728,612 (according to UCSC Genome Browser hg 19 human genome assembly).

In one embodiment of this aspect and all other aspects described herein, the at least one epigenetic modification in the genomic DNA of the cell on chromosome 2 indirectly or directly affects the location 60,716,189-60,728,612 of chromosome 2.

As used herein, “indirectly affecting the location 60,716,189-60,728,612 of chromosome 2” refers to long distance effects of epigenetic modification in the genomic DNA of the cell on chromosome 2 the location 60,716,189-60,728,612 of chromosome 2.

In another embodiment of this aspect and all other aspects described herein, the contacting of any cell described herein comprises contact with an agent that binds the genomic DNA of the cell on chromosome 2 location 60,716,189-60,728,612 (according to UCSC Genome Browser hg 19 human genome assembly), and produces an epigenetic modification on chromosome 2, thereby reducing the mRNA or protein expression of BCL11A.

In another embodiment of this aspect and all other aspects described herein, the contacting of any cell described herein comprises contact with an effective amount of a composition comprising at least a DNA-targeting enzyme or a vector carrying the coding sequence of a DNA-targeting enzyme whereby the DNA-targeting enzyme produces an epigenetic modification on chromosome 2, thereby reducing the mRNA or protein expression of BCL11A.

In another embodiment of this aspect and all other aspects described herein, the contacting of any cell described herein comprises contact with an effective amount of a composition comprising at least a DNA-targeting enzyme or a vector carrying the coding sequence of a DNA-targeting enzyme whereby the DNA-targeting enzyme produces an epigenetic modification on chromosome 2 location 60,716,189-60,728,612 (according to UCSC Genome Browser hg 19 human genome assembly) thereby reducing the mRNA or protein expression of BCL11A. In one aspect, fetal hemoglobin expression is increased in the mammal, relative to expression prior to the contacting.

In another embodiment of this aspect and all other aspects described herein, the hematopoietic progenitor cell, the isolated human cell, or isolated cell is contacted ex vivo or in vitro.

In another embodiment of this aspect and all other aspects described herein, the at least one genetic modification is a deletion.

In another embodiment of this aspect and all other aspects described herein, the deletion comprises one or more of the DNAse 1-hypersensitive sites (DHS) +62, +58, and +55 as described herein in the Examples section. In another embodiment of this aspect and all other aspects described herein, the deletion consists essentially of one or more of the DNAse 1-hypersensitive sites (DHS) +62, +58, and +55 as described herein in the Examples section. In another embodiment, the deletion consists of one or more of the DNAse 1-hypersensitive sites (DHS) +62, +58, and +55 as described herein in the Examples section.

In another embodiment of this aspect and all other aspects described herein, the epigenetic modification comprises or affects one or more of the DNAse 1-hypersensitive sites (DHS) +62, +58, and +55 as described herein in the Examples section. As used herein, the phrase “affects one or more of the DNAse 1-hypersensitive sites” means natural function of these DNAse 1-hypersensitive sites (DHS) +62, +58, and +55 are reduce, for example, access to transcription factors or DNA degradation enzymes such as DNase I. In general, DNase I hypersensitive sites (DHSs) are regions of chromatin which are sensitive to cleavage by the DNase I enzyme. In these specific regions of the genome, chromatin has lost its condensed structure, exposing the DNA, and making it accessible. This raises the availability of DNA to degradation by enzymes, like DNase I. These accessible chromatin zones are functionally related to transcriptional activity, since this remodeled state is necessary for the binding of proteins such as transcription factors. Accordingly, the epigenetic modification contemplated herein results in reduced access to DNA degradation enzymes that is at least 5% lower is at least 10% lower, at least 20% lower, at least 30% lower, at least 40% lower, at least 50% lower, at least 60% lower, at least 70% lower, at least 80% lower, at least 90% lower, at least 1-fold lower, at least 2-fold lower, at least 5-fold lower, at least 10 fold lower, at least 100 fold lower, at least 1000-fold lower, or more compared to a control cell that is not treated in any method disclosed herein.

In another embodiment of this aspect and all other aspects described herein, the deletion comprises one or more of the SNP markers described in Table 2. In another embodiment of this aspect and all other aspects described herein, the deletion consists essentially of one or more of the SNP markers described in Table 2. In another embodiment of this aspect and all other aspects described herein, the deletion consists of one or more of the SNP markers described in Table 2.

In another embodiment of this aspect and all other aspects described herein, the epigenetic modification comprises or affects one or more of the SNP markers described in Table 2. As used herein, the phrase “affects one or more of the SNP markers” means natural function(s) of these SNPs are reduce, for example, access to transcription factors. For example, methylation of these SNPs would reduce the binding of transcription factors, leading to reduced mRNA or protein expression of BCL11A.

In another embodiment of this aspect and all other aspects described herein, the deletion comprises one or more of the fragments listed in Table 7. In another embodiment of this aspect and all other aspects described herein, the deletion consists essentially of one or more of the fragments listed in Table 7. In another embodiment of this aspect and all other aspects described herein, the deletion consists of one or more of the fragments listed in Table 7. In another embodiment of this aspect and all other aspects described herein, the deletion is from 60,716,189 to 60,728,612, from 60,716,189 to 60,723,870, from 60,722,992 to 60,728,612, from 60,717,236 to 60,719,036, from 60,722,006 to 60,723,058, from 60,724,917 to 60,726,282, from 60,616,396 to 60,618,032, from 60,623,536 to 60,624,989, from 60,626,565 to 60,628,177, from 60,717,236 to 60,719,036, from 60,721,212 to 60,722,958, from 60,724,780 to 60,726,471, from 60,739,075 to 60,740,154, from 60,748,003 to 60,749,009, from 60,826,438 to 60,827,601, or from 60,831,589 to 60,833,556.

In another embodiment of this aspect and all other aspects described herein, the epigenetic modification comprises or affects one or more of the fragments listed in Table 7. As used herein, the phrase “affects one or more of the fragments listed in Table 7” means natural function(s) of these fragments are reduce, for example, access to transcription factors. For example, methylation of these fragments would reduce the binding of transcription factors, leading to reduced mRNA or protein expression of BCL11A.

In another embodiment of this aspect and all other aspects described herein, the epigenetic modification is from 60,716,189 to 60,728,612, from 60,716,189 to 60,723,870, from 60,722,992 to 60,728,612, from 60,717,236 to 60,719,036, from 60,722,006 to 60,723,058, from 60,724,917 to 60,726,282, from 60,616,396 to 60,618,032, from 60,623,536 to 60,624,989, from 60,626,565 to 60,628,177, from 60,717,236 to 60,719,036, from 60,721,212 to 60,722,958, from 60,724,780 to 60,726,471, from 60,739,075 to 60,740,154, from 60,748,003 to 60,749,009, from 60,826,438 to 60,827,601, or from 60,831,589 to 60,833,556.

In another embodiment of this aspect and all other aspects described herein, the deletion removes the entire region between chromosome 2 location 60,716,189-60,728,612 or removes a portion of the region resulting in disruption of one or more DNAse 1-hypersensitive sites (DHS). As used herein, the term “disruption” refers to a decrease in erythroid transcription of BCL11A in a cell comprising a disruption of one or more DNAse -1 hypersensitive sites by at least 10% (e.g., at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, at least 99% or even 100% (i.e., no detectable erythroid transcription)) compared to a cell not having such a disruption. In one embodiment, the disruption comprises an inability of a modified DNAse-1hypersensitive site to bind to its native transcription factors (e.g., GATA1 and TAL1).

In another embodiment of this aspect and all other aspects described herein, the epigenetic modification that interferes with the establishment and/or maintenance of the epigenetic signature at the enhancer region on chromosome 2 location 60,716,189-60,728,612 (according to UCSC Genome Browser hg 19 human genome assembly) thereby leading to reduced mRNA or protein expression of BCL11A, and increasing fetal hemoglobin expression in the mammal.

In one embodiment of this aspect and all other aspects described herein, the epigenetic modification that interferes with the establishment and/or maintenance of the epigenetic signature at the enhancer region on chromosome 2 location 60,716,189-60,728,612 (according to UCSC Genome Browser hg 19 human genome assembly) includes but is not limited to epigenetic modifications that affects DNase I sensitivity, epigenetic modifications that affects histone modifications, epigenetic modifications that affects GATA1/TAL1 binding, and epigenetic modifications that affects long-range promoter interaction of the promoter of BCL11A.

For example, an epigenetic modification that interferes with the establishment and/or maintenance of the epigenetic signature at the enhancer region on chromosome 2 location 60,716,189-60,728,612 include but is not limited to at least one deletion within chromosome 2 location 60,716,189-60,728,612 such that the overall function of this region is affected whereby the mRNA and expression of BCL11A is reduced or decreased. For example, the deletion is at the DNaseI sensitivity regions chromosome 2 location 60,716,189-60,728,612, e.g., +62, +58, and +55. The deletion could be at +62 or +58 or +55 or combination thereof. For examples, at +62 and +58, +58 and +55, +62 and +55, or at all three +62, +58, and +55.

As another example, an epigenetic modification that interferes with the establishment and/or maintenance of the epigenetic signature at the enhancer region on chromosome 2 location 60,716,189-60,728,612 include but is not limited to changes in the histone modifications on chromosome 2 that is not at location 60,716,189-60,728,612, or changes in the histone modifications on chromosome 2 at location 60,716,189-60,728,612, or both histone modifications on chromosome 2 not at location 60,716,189-60,728,612 as well as at location 60,716,189-60,728,612 such that the overall function of this region is affected whereby the mRNA and expression of BCL11A is reduced or decreased.

In another embodiment, an epigenetic modification that interferes with the establishment and/or maintenance of the epigenetic signature at the enhancer region on chromosome 2 location 60,716,189-60,728,612 include but is not limited to an insertion of at least one engineered specific-repressor sequence that change the epigenetic features of noncoding elements at chromosome 2 location 60,716,189-60,728,612 and thus result in repression of target gene expression. The first is specifically focused on epigenetically repressing individual enhancers. In other words, insertion of engineered specific-repressor sequences into chromosome 2 would prospectively interfering with epigenetic modification at the BCL11A erythroid enhancer which eventually leads to reduced BCL11A gene expression.

Any methods known in the art can be used to produce the epigenetic modification contemplated. For example, as described in Mendenhall E. M. et al., Nat. Biotechnol. 08 Sep. 2013, and Maeder M L et al., Nat Biotechnol. 09 Oct. 2013 2013.

In one embodiment of this aspect and all other aspects described herein, the insertion of at least one engineered specific-repressor sequence on any location chromosome 2 results in but is not limited to reduced DNaseI sensitivity regions at chromosome 2 location 60,716,189-60,728,612, e.g., +62, +58, and +55; increased histone modifications on chromosome 2 location 60,716,189-60,728,612; reduced transcription factors binding to the GATA1/TAL1 of the enhancer region on chromosome 2 location 60,716,189-60,728,612; and reduced or weakened interaction between the chromosome 2 location 60,716,189-60,728,612 with the BCL11A promoter.

In one embodiment of this aspect and all other aspects described herein, the overall effects of the insertion of at least one engineered specific-repressor sequence on any location chromosome 2 is reduced or decreased mRNA and expression of BCL11A.

In some embodiments, as used in the context of mRNA and expression of BCL11A, interaction between the chromosome 2 location 60,716,189-60,728,612 or BCL11A enhancer with the BCL11A promoter, and transcription factors binding to the GATA1/TAL1 of the enhancer region, the term “reduced” or “decreased” refers to at least 5% lower is at least 10% lower, at least 20% lower, at least 30% lower, at least 40% lower, at least 50% lower, at least 60% lower, at least 70% lower, at least 80% lower, at least 90% lower, at least 1-fold lower, at least 2-fold lower, at least 5-fold lower, at least 10 fold lower, at least 100 fold lower, at least 1000-fold lower, or more compared to the control situation that is in the absence of the epigenetic modification or insertion of engineered sequences disclosed herein. By decrease of the BCL11A mRNA or protein expression in the cell means that protein expression is at least 5% lower is at least 10% lower, at least 20% lower, at least 30% lower, at least 40% lower, at least 50% lower, at least 60% lower, at least 70% lower, at least 80% lower, at least 90% lower, at least 1-fold lower, at least 2-fold lower, at least 5-fold lower, at least 10 fold lower, at least 100 fold lower, at least 1000-fold lower, or more compared to a control cell that does not have the epigenetic modification or insertion of engineered sequences disclosed herein.

In one embodiment of this aspect and all other aspects described herein, the insertion of at least one engineered specific-repressor sequence occurs within the DNaseI sensitivity regions of chromosome 2 location 60,716,189-60,728,612, e.g., +62, +58, and +55. The insertion could be at the 5′end of +62 or +58 or +55 or at the 3′ end of +62 or +58 or +55, or between +62 and +58, or between +58 and +55, or between +55 and +62.

In one embodiment of this aspect and all other aspects described herein, the insertion of at least one engineered specific-repressor sequence changes the DNaseI sensitivity regions of chromosome 2 location 60,716,189-60,728,612.

In one embodiment of this aspect and all other aspects described herein, the epigenetic modifications changes the DNaseI sensitivity regions of chromosome 2 location 60,716,189-60,728,612.

In one embodiment of this aspect and all other aspects described herein, the epigenetic modifications changes the histone modifications on chromosome 2 location 60,716,189-60,728,612.

In one embodiment of this aspect and all other aspects described herein, the insertion of at least one engineered specific-repressor sequence changes the histone modifications on chromosome 2 location 60,716,189-60,728,612.

In one embodiment of this aspect and all other aspects described herein, the epigenetic modifications changes the GATA1/TAL1 binding of the enhancer region on chromosome 2 location 60,716,189-60,728,612 such that the overall function of this region is affected whereby the mRNA and expression of BCL11A is reduced or decreased. For example, the binding of transcription factors to the GATA1/TAL1.

In one embodiment of this aspect and all other aspects described herein, the insertion of at least one engineered specific-repressor sequence occurs within the GATA1/TAL1 as described herein. The insertion can be at the 5′ end or 3′end of GATA1/TAL1. The insertion can be between GATA1 and TAL1. The insertion changes the GATA1/TAL1 binding of the enhancer region on chromosome 2 location 60,716,189-60,728,612 such that the overall function of this region is affected whereby the mRNA and expression of BCL11A is reduced or decreased. For example, the binding of transcription factors to the GATA1/TAL1.

In one embodiment of this aspect and all other aspects described herein, the epigenetic modification changes the interaction between the BCL11A enhancer and the BCL11A promoter. In one embodiment, the interaction is reduced or weakened such that the overall function of this region is affected whereby the mRNA and expression of BCL11A is reduced or decreased.

In one embodiment of this aspect and all other aspects described herein, the epigenetic modifications changes the interaction between the chromosome 2 location 60,716,189-60,728,612 with the BCL11A promoter. In one embodiment, the interaction is reduced or weakened such that the overall function of this region is affected whereby the mRNA and expression of BCL11A is reduced or decreased.

Also provided herein in another aspect is an isolated genetic engineered human cell having at least one genetic modification on chromosome 2 location 60,716,189-60,728,612 (according to UCSC Genome Browser hg 19 human genome assembly) made by the process of contacting the cell with an effective amount of a composition comprising at least a DNA-targeting endonuclease or a vector carrying the coding sequence of a DNA-targeting endonuclease whereby the DNA-targeting endonuclease cleaves the genomic DNA of the cell on chromosome 2 location 60,716,189-60,728,612 causing at least one genetic modification therein.

In one embodiment of this aspect and all other aspects described herein, the isolated genetic engineered human cell having at least one epigenetic modification at the genomic DNA of the cell on chromosome 2. In another of this aspect and all other aspects described herein, the isolated genetic engineered human cell having at least one epigenetic modification at the genomic DNA of the cell on chromosome 2 location 60,716,189-60,728,612.

In some aspects of any of these isolated genetic engineered human cells having at least one epigenetic modification, the cells are transplanted into a mammal for use in increasing the fetal hemoglobin in the mammal.

In one embodiment of this aspect and all other aspects described herein, the isolated genetic engineered human cell having at least one genetic modification at the genomic DNA of the cell on chromosome 2 location 60,716,189-60,728,612 is transplanted into a mammal for use in increasing the fetal hemoglobin in the mammal.

In one embodiment of this aspect and all other aspects described herein, the isolated genetic engineered human cell having at least one genetic modification at the genomic DNA of the cell on chromosome 2 location 60,716,189-60,728,612 is stored for later use by cryopreservation.

In some aspects of any of those isolated genetic engineered human cells having at least one epigenetic modification, the cells are stored for later use by cryopreservation.

In one embodiment of this aspect and all other aspects described herein, the isolated genetic engineered human cell having at least one genetic modification at the genomic DNA of the cell on chromosome 2 location 60,716,189-60,728,612 is cryopreserved, thawed and transplanted into mammal for use in increasing the fetal hemoglobin in the mammal.

In some aspects of any of those isolated genetic engineered human cells having at least one epigenetic modification, cryopreserved, thawed and transplanted into mammal for use in increasing the fetal hemoglobin in the mammal.

Another aspect provided herein relates to a composition comprising isolated genetic engineered human cells, wherein the cells have at least one genetic modification on chromosome 2 location 60,716,189-60,728,612 (according to UCSC Genome Browser hg 19 human genome assembly) made by the process of contacting the cells with an effective amount of a composition comprising at least a DNA-targeting endonuclease or a vector carrying the coding sequence of a DNA-targeting endonuclease whereby the DNA-targeting endonuclease cleaves the genomic DNA of the cell on chromosome 2 location 60,716,189-60,728,612 (according to UCSC Genome Browser hg 19 human genome assembly) causing at least one genetic modification therein.

Another aspect provided herein relates to a composition comprising isolated genetic engineered human cells, wherein the cells have at least one epigenetic modification on chromosome 2. In one embodiment, the at least one epigenetic modification on chromosome 2 is at location 60,716,189-60,728,612 (according to UCSC Genome Browser hg 19 human genome assembly). In another embodiment, at least one epigenetic modification on chromosome 2 is made by the process of contacting the cells with an effective amount of a composition comprising at least a DNA-targeting enzyme or a vector carrying the coding sequence of a DNA-targeting enzyme whereby the DNA-targeting enzyme produces at least one epigenetic modification in the genomic DNA of the cell on chromosome 2 which affects the location 60,716,189-60,728,612 (according to UCSC Genome Browser hg 19 human genome assembly) causing therein.

In one embodiment of this aspect and all other aspects described herein, the composition causes an increase in fetal hemoglobin mRNA or protein expression in the contact cell.

In one embodiment of this aspect and all other aspects described herein, the cells of any compositions described are autologous, to the mammal who is the recipient of the cells in a transplantation procedure, ie., the cells of the composition are derived or harvested from the mammal prior to any described modification.

In one embodiment of this aspect and all other aspects described herein, the cells of any compositions described are non-autologous to the mammal who is the recipient of the cells in a transplantation procedure, ie., the cells of the composition are not derived or harvested from the mammal prior to any described modification.

In one embodiment of this aspect and all other aspects described herein, the cells of any compositions described are at the minimum HLA type matched with to the mammal who is the recipient of the cells in a transplantation procedure.

In one embodiment of this aspect and all other aspects described herein, the cells of any compositions described are isolated progenitor cells prior to any described modification.

In one embodiment of this aspect and all other aspects described herein, the cells of any compositions described are isolated hematopoietic progenitor cells prior to any described modification.

In one embodiment of this aspect and all other aspects described herein, the cells of any compositions described are isolated induced pluripotent stem cells prior to any described modification.

In another embodiment of this aspect and all other aspects described herein, the deletion comprises one or more of the DNAse 1-hypersensitive sites (DHS) +62, +58, and +55 as described herein in the Examples section. In another embodiment of this aspect and all other aspects described herein, the deletion consists essentially of one or more of the DNAse 1-hypersensitive sites (DHS) +62, +58, and +55 as described herein in the Examples section. In another embodiment, the deletion consists of one or more of the DNAse 1-hypersensitive sites (DHS) +62, +58, and +55 as described herein in the Examples section. In one embodiment, as used herein, the term “portion” in the context of genomic deletion is at least 10% to about 100% of the specified region. In other embodiments, the portion deleted is at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, at least 99% or even 100% of the specified region.

In another embodiment of this aspect and all other aspects described herein, the deletion comprises one or more of the SNP markers described in Table 2. In another embodiment of this aspect and all other aspects described herein, the deletion consists essentially of one or more of the SNP markers described in Table 2. In another embodiment of this aspect and all other aspects described herein, the deletion consists of one or more of the SNP markers described in Table 2.

In another embodiment of this aspect and all other aspects described herein, the deletion comprises one or more of the fragments listed in Table 7. In another embodiment of this aspect and all other aspects described herein, the deletion consists essentially of one or more of the fragments listed in Table 7. In another embodiment of this aspect and all other aspects described herein, the deletion consists of one or more of the fragments listed in Table 7. In another embodiment of this aspect and all other aspects described herein, the deletion is from 60,716,189 to 60,728,612, from 60,716,189 to 60,723,870, from 60,722,992 to 60,728,612, from 60,717,236 to 60,719,036, from 60,722,006 to 60,723,058, from 60,724,917 to 60,726,282, from 60,616,396 to 60,618,032, from 60,623,536 to 60,624,989, from 60,626,565 to 60,628,177, from 60,717,236 to 60,719,036, from 60,721,212 to 60,722,958, from 60,724,780 to 60,726,471, from 60,739,075 to 60,740,154, from 60,748,003 to 60,749,009, from 60,826,438 to 60,827,601, or from 60,831,589 to 60,833,556.

In another embodiment of this aspect and all other aspects described herein, the deletion removes the entire region between chromosome 2 location 60,716,189-60,728,612 (according to UCSC Genome Browser hg 19 human genome assembly) or removes a portion of the region resulting in disruption of one or more DNAse 1-hypersensitive sites (DHS).

In one embodiment of this aspect and all other aspects described herein, the method further comprises selecting a mammal in need of increasing fetal hemoglobin.

In one embodiment of this aspect and all other aspects described herein, the mammal has been diagnosed with a hemoglobinopathy.

In one embodiment of this aspect and all other aspects described herein, the mammal in need of increasing fetal hemoglobin has been diagnosed with a hemoglobinopathy.

In one embodiment of this aspect and all other aspects described herein, the hemoglobinopathy is a β-hemoglobinopathy.

In one embodiment of this aspect and all other aspects described herein, the hemoglobinopathy is sickle cell disease.

In one embodiment of this aspect and all other aspects described herein, the hemoglobinopathy is β-thalassemia.

In one embodiment of this aspect and all other aspects described herein, the contacted cell, human cell, hematopoietic progenitor cell or its progeny is administered to the mammal.

In one embodiment, this disclosure provides a method for increasing fetal hemoglobin levels in a mammal in need thereof, the method comprising the steps of providing an isolated population of hematopoietic progenitor cells or hematopoietic stem cells from the mammal in ex vivo, and contacting the population of hematopoietic progenitor or stem cells with an effective amount of a composition comprising at least a DNA-targeting endonuclease or a vector carrying the coding sequence of a DNA-targeting endonuclease whereby the DNA-targeting endonuclease cleaves the genomic DNA of the cell on chromosome 2 location 60,716,189-60,728,612 causing at least one genetic modification therein, whereby fetal hemoglobin expression is increased in the mammal, relative to expression prior to the contacting. In further embodiment of this method, the contacted population of hematopoietic progenitor or stem cells having increased fetal hemoglobin expression is cryopreserved and stored or reintroduced into the mammal. In another embodiment, the cryopreserved population of hematopoietic progenitor or stem cells having increased fetal hemoglobin expression is thawed and then reintroduced into the mammal. In further embodiment of this method, the method comprises chemotherapy and/or radiation therapy to remove or reduced the endogenous hematopoietic progenitor or stem cells in the mammal. In any of the embodiment of the described method, the hematopoietic progenitor or stem cells can be substituted with an iPSCs described herein.

In one embodiment, this disclosure provides a method for increasing fetal hemoglobin levels in a mammal in need thereof, the method comprising the steps of isolating a population of hematopoietic progenitor cells or hematopoietic stem cells from the mammal, and contacting in ex vivo the population of hematopoietic progenitor or stem cells with an effective amount of a composition comprising at least a DNA-targeting endonuclease or a vector carrying the coding sequence of a DNA-targeting endonuclease whereby the DNA-targeting endonuclease cleaves the genomic DNA of the cell on chromosome 2 location 60,716,189-60,728,612 causing at least one genetic modification therein, whereby fetal hemoglobin expression is increased in the mammal, relative to expression prior to the contacting. In further embodiment of this method, the ex vivo contacted population of hematopoietic progenitor or stem cells having increased fetal hemoglobin expression is cryopreserved and stored or reintroduced into the mammal. In another embodiment, the cryopreserved population of hematopoietic progenitor or stem cells having increased fetal hemoglobin expression is thawed and then reintroduced into the mammal. In further embodiment of this method, the method comprises chemotherapy and/or radiation therapy to remove or reduced the endogenous hematopoietic progenitor or stem cells in the mammal. In any of the embodiment of the described method, the hematopoietic progenitor or stem cells can be substituted with an iPSCs derived from the mammal. In any embodiment of the method, the method further comprises selecting a mammal in need of increased fetal hemoglobin expression.

In one embodiment, this disclosure provides a method for increasing fetal hemoglobin levels in a mammal in need thereof, the method comprising the steps of providing isolating a population of hematopoietic progenitor cells or hematopoietic stem cells from the mammal and deleting the genomic DNA of the cells on chromosome 2 location 60,716,189-60,728,612 causing at least one genetic modification therein, whereby fetal hemoglobin expression is increased in said mammal, relative to expression prior to said contacting. In further embodiment of this method, the population of hematopoietic progenitor or stem cells with deleted genomic DNA and having increased fetal hemoglobin expression is cryopreserved and stored or reintroduced into the mammal. In another embodiment, the population of hematopoietic progenitor or stem cells with deleted genomic DNA and having increased fetal hemoglobin expression is thawed and then reintroduced into the mammal. In further embodiment of this method, the method comprises chemotherapy and/or radiation therapy to remove or reduced the endogenous hematopoietic progenitor or stem cells in the mammal. In any of the embodiment of the described method, the hematopoietic progenitor or stem cells can be substituted with an iPSCs described herein. In any of the embodiment of the described method, the hematopoietic progenitor or stem cells or iPSCs are analogous to the mammal, meaning the cells are derived from the same mammal. In another of the embodiment of the described method, the hematopoietic progenitor or stem cells or iPSCs are non-analogous to the mammal, meaning the cells are not derived from the same mammal, but another mammal of the same species. For example, the mammal is a human. In any embodiment of the method, the method further comprises selecting a mammal in need of increased fetal hemoglobin expression.

In one embodiment, this disclosure provides a method for increasing fetal hemoglobin levels in a mammal in need thereof, the method comprising the steps of isolating a population of hematopoietic progenitor cells or hematopoietic stem cells from the mammal and ex vivo deleting the genomic DNA of the cells on chromosome 2 location 60,716,189-60,728,612 causing at least one genetic modification therein, whereby fetal hemoglobin expression is increased in said mammal, relative to expression prior to said contacting. In further embodiment of this method, the population of hematopoietic progenitor or stem cells with deleted genomic DNA and having increased fetal hemoglobin expression is cryopreserved and stored or reintroduced into the mammal. In another embodiment, the cryopreserved population of hematopoietic progenitor or stem cells having increased fetal hemoglobin expression is thawed and then reintroduced into the mammal. In further embodiment of this method, the method comprises chemotherapy and/or radiation therapy to remove or reduced the endogenous hematopoietic progenitor or stem cells in the mammal. In any of the embodiment of the described method, the hematopoietic progenitor or stem cells can be substituted with an iPSCs derived from the mammal. In any embodiment of the method, the method further comprises selecting a mammal in need of increased fetal hemoglobin expression.

In one embodiment of any method described, the method further comprises selecting a mammal in need of increased fetal hemoglobin expression. Exemplary mammal in need of increased fetal hemoglobin expression is one that has been diagnosed with a hemoglobinopathy.

In one embodiment, this disclosure provides a method of treatment of a hemoglobinopathy in a mammal comprising the steps of (a) providing hematopoietic progenitor cells or hematopoietic stem cells or iPSCs; (b) contacting the cells ex vivo or in vitro with an effective amount of a composition comprising at least a DNA-targeting endonuclease or a vector carrying the coding sequence of a DNA-targeting endonuclease whereby the DNA-targeting endonuclease cleaves the genomic DNA of the cell on chromosome 2 location 60,716,189-60,728,612 causing at least one genetic modification therein, whereby fetal hemoglobin expression is increased in said mammal, relative to expression prior to said contacting; and (c) administering the cells of step (b) into the mammal.

In one embodiment of any method, the cells after step (b) can be cryopreserved till they are needed for administration into the mammal. In further embodiment of this method, the method comprises chemotherapy and/or radiation therapy to remove or reduced the endogenous hematopoietic progenitor or stem cells in the mammal. In any of the embodiment of the described method, the hematopoietic progenitor or stem cells or iPSCs are autologous to the mammal, meaning the cells are derived from the same mammal. In another of the embodiment of the described method, the hematopoietic progenitor or stem cells or iPSCs are non-autologous to the mammal, meaning the cells are not derived from the same mammal, but another mammal of the same species. For example, the mammal is a human.

In one embodiment of any method described, the method further comprises selecting a mammal in need of treatment of a hemoglobinopathy.

In one embodiment, this disclosure provides a method of treatment of a hemoglobinopathy in a mammal comprising the steps of (a) isolating hematopoietic progenitor cells or hematopoietic stem cells from the mammal;(b) contacting the cells ex vivo or in vitro with an effective amount of a composition comprising at least a DNA-targeting endonuclease or a vector carrying the coding sequence of a DNA-targeting endonuclease whereby the DNA-targeting endonuclease cleaves the genomic DNA of the cell on chromosome 2 location 60,716,189-60,728,612 causing at least one genetic modification therein, whereby fetal hemoglobin expression is increased in the mammal, relative to expression prior to said contacting; and (c) administering the cells of step (b) into the mammal.

In one embodiment, the cells after step (b) can be cryopreserved till they are needed for administration into the mammal. In any embodiment of the method, the method further comprises selecting a mammal in need of treatment of a hemoglobinopathy.

In one embodiment, this disclosure provides a method of treatment of a hemoglobinopathy in a mammal comprising the steps of: (a) providing hematopoietic progenitor cells or hematopoietic stem cells or iPSCs; (b) ex vivo deleting the genomic DNA of the cells on chromosome 2 location 60,716,189-60,728,612 causing at least one genetic modification therein, whereby fetal hemoglobin expression is increased in said mammal, relative to expression prior to said contacting; and (c) administering the cells of step (b) into the mammal.

In one embodiment, the cells after step (b) can be cryopreserved till they are needed for administration into the mammal. In further embodiment of this method, the method comprises chemotherapy and/or radiation therapy to remove or reduced the endogenous hematopoietic progenitor or stem cells in the mammal. In any of the embodiment of the described method, the hematopoietic progenitor or stem cells or iPSCs are analogous to the mammal, meaning the cells are derived from the same mammal. In another of the embodiments of the described method, the hematopoietic progenitor or stem cells or iPSCs are non-analogous to the mammal, meaning the cells are not derived from the same mammal, but another mammal of the same species. For example, the mammal is a human. In any embodiment of the method, the method further comprises selecting a mammal in need of treatment of a hemoglobinopathy.

In one embodiment, this disclosure provides a method of treatment of a hemoglobinopathy in a mammal comprising the steps of: (a) isolating hematopoietic progenitor cells or hematopoietic stem cells from the mammal; (b) ex vivo deleting the genomic DNA of the cells on chromosome 2 location 60,716,189-60,728,612 causing at least one genetic modification therein, whereby fetal hemoglobin expression is increased in the mammal, relative to expression prior to said contacting; and (c) administering the cells of step (b) into the mammal.

In one embodiment, the cells after step (b) can be cryopreserved till they are needed for administration into the mammal. In further embodiment of this method, the method comprises chemotherapy and/or radiation therapy to remove or reduced the endogenous hematopoietic progenitor or stem cells in the mammal. In any embodiment of the method, the method further comprises selecting a mammal in need of treatment of a hemoglobinopathy.

In one embodiment, this disclosure provides a method of treatment of a hemoglobinopathy in a mammal (e.g. a human) comprising introducing a composition described herein comprising isolated genetic engineered cells having at least one genetic modification on chromosome 2 location 60,716,189-60,728,612 whereby fetal hemoglobin expression is increased in the mammal. In further embodiment of this method, the method comprises chemotherapy and/or radiation therapy to remove or reduced the endogenous hematopoietic progenitor or stem cells in the mammal. In any embodiment of the method, the method further comprises selecting a mammal in need of treatment of a hemoglobinopathy.

In one embodiment, this disclosure provides a method of treatment of a hemoglobinopathy in a mammal (e.g. a human) comprising increasing fetal hemoglobin expression in the mammal by method described herein.

In any embodiment of any treatment method described, the hemoglobinopathy is a β-hemoglobinopathy.

In any embodiment of any treatment method described, the hemoglobinopathy is β-thalassemia.

In any embodiment of any treatment method described, the hemoglobinopathy is sickle cell anemia.

In one of embodiment of any described method, the hematopoietic progenitor or stem cells or iPSCs are autologous to the mammal, meaning the cells are derived from the same mammal. In another of the embodiment of any described method, the hematopoietic progenitor or stem cells or iPSCs are non-autologous to the mammal, meaning the cells are not derived from the same mammal, but another mammal of the same species. For example, the mammal is a human.

In one of embodiment of any described method, the contacting of any cell described herein can be ex vivo or in vitro or in vivo.

In another embodiment of any described method, the contacting of any cell described herein comprises contact with an agent that binds the genomic DNA of the cell on chromosome 2 and produces an epigenetic modification in the genome of the cell on chromosome 2, thereby reducing the mRNA or protein expression of BCL11A. In one embodiment, the epigenetic modification is on chromosome 2 location 60,716,189-60,728,612 (according to UCSC Genome Browser hg 19 human genome assembly).

In another embodiment of any described method, the contacting of any cell described herein comprises contact with an agent that binds the genomic DNA of the cell on chromosome 2 location 60,716,189-60,728,612 (according to UCSC Genome Browser hg 19 human genome assembly), and produces an epigenetic modification on chromosome 2, thereby reducing the mRNA or protein expression of BCL11A.

In another embodiment of any described method, the contacting of any cell described herein comprises contact with an effective amount of a composition comprising at least a DNA-targeting enzyme or a vector carrying the coding sequence of a DNA-targeting enzyme whereby the DNA-targeting enzyme produces an epigenetic modification on chromosome 2, thereby reducing the mRNA or protein expression of BCL11A.

In another embodiment of any described method, the contacting of any cell described herein comprises contact with an effective amount of a composition comprising at least a DNA-targeting enzyme or a vector carrying the coding sequence of a DNA-targeting enzyme whereby the DNA-targeting enzyme produces an epigenetic modification on chromosome 2 location 60,716,189-60,728,612 (according to UCSC Genome Browser hg 19 human genome assembly) thereby reducing the mRNA or protein expression of BCL11A. In one aspect, fetal hemoglobin expression is increased in the mammal, relative to expression prior to the contacting.

In another embodiment of any described method, the hematopoietic progenitor cell, the isolated human cell, or isolated cell is contacted ex vivo or in vitro.

In another embodiment of any described method, the at least one genetic modification is a deletion. In another embodiment of this aspect and all other aspects described herein, the at least one epigenetic modification is a deletion.

In one embodiment, provided herein is a use of an agent that binds the genomic DNA of the cell on chromosome 2 location 60,716,189-60,728,612 (according to UCSC Genome Browser hg 19 human genome assembly) for increasing the fetal hemoglobin in a mammal or for the treatment of a hemoglobinopathy in the mammal or for reducing the mRNA or expression of BCL11A, wherein the mRNA or protein expression of BCL11A is reduced.

In one embodiment, provided herein is a use of an effective amount of a composition comprising at least a DNA-targeting endonuclease or a vector carrying the coding sequence of a DNA-targeting endonuclease for increasing the fetal hemoglobin in a mammal or for the treatment of a hemoglobinopathy in the mammal or for reducing the mRNA or expression of BCL11A, wherein the DNA-targeting endonuclease cleaves the genomic DNA of the cell on chromosome 2 location 60,716,189-60,728,612 causing at least one genetic modification therein.

In one embodiment, provided herein is a use of an effective amount of a composition comprising at least a DNA-targeting enzyme or a vector carrying the coding sequence of a DNA-targeting enzyme for increasing the fetal hemoglobin in a mammal or for the treatment of a hemoglobinopathy in the mammal or for reducing the mRNA or expression of BCL11A, wherein the DNA-targeting enzyme produces at least one epigenetic modification in the genomic DNA of the cell on chromosome 2, thereby affecting the mRNA or expression of BCL11A. In one embodiment, the at least one epigenetic modification is at location 60,716,189-60,728,612. In another embodiment, the effect of the one epigenetic modification is reducing the mRNA or protein expression of BCL11A.

In one embodiment, provided herein is a use of any isolated cells described herein for increasing the fetal hemoglobin in a mammal or for the treatment of a hemoglobinopathy in the mammal.

In one embodiment, provided herein is a use of a composition comprising isolated genetic engineered human cells for increasing the fetal hemoglobin in a mammal or for the treatment of a hemoglobinopathy in the mammal, wherein the cells have at least one genetic modification on chromosome 2 location 60,716,189-60,728,612 (according to UCSC Genome Browser hg 19 human genome assembly) made by the process of contacting the cells with an effective amount of a composition comprising at least a DNA-targeting endonuclease or a vector carrying the coding sequence of a DNA-targeting endonuclease whereby the DNA-targeting endonuclease cleaves the genomic DNA of the cell on chromosome 2 location 60,716,189-60,728,612 (according to UCSC Genome Browser hg 19 human genome assembly) causing at least one genetic modification therein.

In one embodiment, provided herein is a use of a composition comprising isolated genetic engineered human cells for increasing the fetal hemoglobin in a mammal or for the treatment of a hemoglobinopathy in the mammal, wherein the cells have at least one epigenetic modification on chromosome 2. In one embodiment, the at least one epigenetic modification on chromosome 2 is at location 60,716,189-60,728,612 (according to UCSC Genome Browser hg 19 human genome assembly). In another embodiment, at least one epigenetic modification on chromosome 2 is made by the process of contacting the cells with an effective amount of a composition comprising at least a DNA-targeting enzyme or a vector carrying the coding sequence of a DNA-targeting enzyme whereby the DNA-targeting enzyme produces at least one epigenetic modification in the genomic DNA of the cell on chromosome 2 which affects the location 60,716,189-60,728,612 (according to UCSC Genome Browser hg 19 human genome assembly) causing therein.

In one embodiment, provided herein is a use of any isolated cells described herein or any one of the compositions described herein for the manufacture of a medicament for increasing the fetal hemoglobin in a mammal or for the treatment of a hemoglobinopathy in the mammal.

In one embodiment of use of the composition described herein, the composition causes an increase in fetal hemoglobin mRNA or protein expression in the contact cell.

In one embodiment of use of the composition described herein, the cells of any compositions described are autologous, to the mammal who is the recipient of the cells in a transplantation procedure, ie., the cells of the composition are derived or harvested from the mammal prior to any described modification.

In one embodiment of use of the composition described herein, the cells of any compositions described are non-autologous to the mammal who is the recipient of the cells in a transplantation procedure, ie., the cells of the composition are not derived or harvested from the mammal prior to any described modification.

In one embodiment of use of the composition described herein, the cells of any compositions described are at the minimum HLA type matched with to the mammal who is the recipient of the cells in a transplantation procedure.

In one embodiment of use of the composition described herein, the cells of any compositions described are isolated progenitor cells prior to any described modification.

In one embodiment of use of the composition described herein, the cells of any compositions described are isolated hematopoietic progenitor cells prior to any described modification.

In one embodiment of use of the composition described herein, the cells of any compositions described are isolated induced pluripotent stem cells prior to any described modification.

In one embodiment of use of the composition described herein, the cells of any compositions described are cryopreserved prior to use.

It is known that there are HbF-associated variations at BCL11A. Six GWAS of HbF level (or the highly correlated trait F-cell number) have been conducted in individuals of European, African and Asian descent, each identifying trait-associated variants within BCL11A (7-12). The same variants are associated with the clinical severity of SCD and β-thalassemia (9, 10, 50), consistent with HbF as a major modifier of these disorders. Variation at BCL11A is estimated to explain ˜15% of the trait variance in HbF level (7, 12, 43). Four different SNPs have been identified as most highly associated with the trait (rs1427407 (7), rs11886868 (8), rs4671393 (9) and rs766432 (10-12)); these sentinel SNPs cluster within 3 kb of each other in BCL11A intron-2 (FIGS. 2A and 11B). Haplotypes including the sentinel SNPs appear to better explain the HbF association than any individual SNP (12, 43). Fifty SNPs at the BCL11A locus and twenty-seven SNPs within intron-2 have been associated with HbF level with genome-wide significance (P<5×10⁻⁸). Despite large-scale resequencing efforts, coding variants of BCL11A have not been described (43).

Previously, the inventors used the CSSCD to fine-map the association signal with HbF at the BCL11A locus and reported a strong association with rs4671393 (43). In that study, rs1427407 was imputed. Two additional SNPs, rs766432 and rs11886868 have also been identified in prior studies as sentinel SNPs most highly trait-associated (8, 10, 11, 51). In a subset of individuals (n=728) for which genotypes at all four sentinel SNPs were available, the association result was not significant at rs4671393, rs766432 or rs11886868 following conditioning on genotypes at rs1427407; conversely, the association remained highly significant for rs1427407 upon conditioning on rs4671393, rs766432 or rs11886868 (Table 4). Therefore, rs1427407 is the SNP most strongly associated with HbF level within the erythroid DHSs and better accounts for the trait association than other previously described sentinel SNPs.

Conditional analysis demonstrated associations that remained significant after conditioning on rs1427407. The most significant residual association was for rs7606173 in DHS +55 (P=9.66×10⁻¹¹); rs7599488 in DHS +62, which we had previously reported (43), was only slightly less significant (P=2.43×10⁻¹⁰) (Table 1). Analysis of rare DNA sequence variants within the three DHSs did not yield additional independent HbF-associated signals (Table 5).

The inventors have found that allele-specific transcription factor (TF) binding are involved with BCL11A expression. Allele-specific biochemical studies were performed using informative heterozygotes to control for trans-acting differences between samples and to ensure equal abundance of both alleles, substantiated by equal representation of alleles in paired gDNA (FIGS. 2B and 2C). rs1427407 is found directly at the center of a GATA1 and TAL1 binding peak at DHS +62 (FIG. 2B). In the ChIP assays performed, chromatin was sonicated to approximately 500-bp fragments. The five primary human erythroid precursor samples heterozygous for rs1427407 used for ChIP-qPCR were Sanger sequenced at the erythroid DHSs. The only other heterozygous SNP within 500-bp of rs1427407 in any of these samples was rs7599488 (304-bp 3′ of rs1427407) which was heterozygous in just two of the five samples. This SNP does not fall within GATA1 or TAL1 binding motifs. It therefore appears unlikely that another SNP within DHS +62 could account for the observed allele-specific TF binding.

In addition, the inventors have found that there is an association between BCL11A expression and HbF level. The inventors' studies provide an estimate of the change in BCL11A expression that may result in a clinically meaningful increase in HbF level. Among a limited set of human lymphoblastoid cell lines were previously reported correlation of the high HbF-associated A-allele of rs4671393 with reduced BCL11A expression (13). Extension of these experiments to a larger collection of genotyped lines failed to confirm this observation. Hence, The inventors have found that the HbF-associated rs1427407-rs7606173 haplotype influence BCL11A expression in an erythroid-specific context, a possibility consistent with the DNase I sensitivity findings BCL11A mRNA expression in primary erythroid precursors differed by 1.7-fold between the high-HbF rs1427407-rs7606173 T-G and low-HbF G-C haplotypes (FIG. 3B); correspondingly, median HbF levels were 10.6% and 3.1% in T-G and G-C homozygotes, respectively (FIG. 3C). Of note, the results demonstrating allele-specific expression of BCL11A in primary human erythroid cells were observed in cells modigygous for the rs1427407-rs7606173 haplotype, and thus the modest effects on BCL11A expression reflect the combined effects of all functional SNPs within the haplotype. While inheritance of a protective BCL11A haplotype is clinically beneficial on a population basis (9, 10, 50), the average level of HbF in T-G homozygotes remains below that required to prevent morbidity from SCD. The sensitivity of HbF level to BCL11A expression, however, predicts that relief of disease severity might require only a modest further reduction in BCL11A expression.

The inventors further investigated the developmental regulation of globin genes and BCL11A. During human development, yolk sac-derived ε-globin is superseded in the first trimester by fetal liver-derived γ-globin. Following birth, as erythropoiesis shifts from the liver to the bone marrow, γ-globin is gradually silenced and β-globin predominates. Only a single switch in globin gene expression occurs in mouse ontogeny. During this transition, which occurs at mid-gestation, the circulating yolk sac-derived primitive erythrocytes express embryonic-stage globins εy and βH1, whereas the fetal liver definitive erythroblasts express adult-stage globins β1 and β2. Concordant with this developmental switch, BCL11A is expressed in the definitive but not primitive-stage erythroid lineage and required for the change in globin gene expression (16, 52).

In the stable transgenic BCL11A +52.0-64.4 reporter lines at 10.5 dpc, lacZ expression was observed only in the fetal liver primordium and not in the circulating blood within the embryo, placenta or yolk sac (FIG. 6A). These results, coupled with the finding of lacZ expression in the 12.5 dpc definitive fetal liver erythroblasts but not yolk sac-derived primitive circulating erythrocytes (FIG. 4B), demonstrate that the BCL11A composite enhancer sequences drive expression in a developmentally-specific pattern concordant with endogenous globin gene switching.

A series of deletion mutants was generated to refine the minimal elements required for erythroid enhancer activity. Sequences containing the central +58 DHS were sufficient for erythroid enhancer activity. Those sequences containing only the flanking +62 or +55 elements were unable to direct erythroid gene expression (FIG. 6B). To test the ability of the DHSs to enhance gene expression in primary human erythroid precursors, we used lentiviral delivery of a GFP reporter system as previously described (39). Similarly, the +58 DHS enhanced gene expression in this reporter assay (FIG. 7).

The inventors decided to generate cell lines with a Bcl11a enhancer deletion to investigate the requirement of the enhancer for BCL11A expression. Stable erythroid cells with disruption of the enhancer were generated. Since there are no suitable adult-stage human erythroid cell lines, and as proof of principle, the inventors turned to the murine system. Mouse erythroleukemia (MEL) cells depend on BCL11A for an adult-stage pattern of globin gene expression (14). The inventors identified an orthologous erythroid composite enhancer at mouse Bcl11a intron-2. Like the human GWAS-marked intron-2 BCL11A enhancer, these sequences possessed a series of erythroid-specific DHSs. In addition, these sequences were decorated by H3K4me1 and H3K27ac, lacked H3K4me3 and H3K27me3, and occupied by both GATA1 and TAL1 in mouse erythroid chromatin (FIG. 8). Composite regulatory elements including a series of adjacent DHSs have been shown to be critical for gene expression at numerous loci, including among others the β-globin locus control region, α-globin multispecies conserved sequences, and IgH regulatory region (53-55). We observed species-specific unique features of the composite enhancer. For example, The inventors identified the conserved mouse sequences to each of the three human DHSs +62, +58 and +55, and found erythroid DNase I hypersensitivity at the +62 and +55 conserved sequences, however the +58 conserved sequences lacked DNase I hypersensitivity.

PCR and Southern blotting verified excision of the +50.4-60.4 kb intronic segment of Bcl11a in three unique MEL clones and two unique pre-B lymphocyte clones (FIG. 9). Sanger-sequenced breakpoints were characteristic of TALEN-mediated cleavage with subsequent NHEJ repair (FIG. 10). Upon deletion of the intronic segment, we observed dramatic reduction in BCL11A transcript in the MEL cell clones by RT-qPCR, using primer pairs detecting exon junctions upstream, spanning or downstream of the deletion (FIG. 5A).

Definitions

For convenience, certain terms employed in the entire application (including the specification, examples, and appended claims) are collected here. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

As used herein, the phrase “agent that binds the genomic DNA of the cell on chromosome 2 location 60,716,189-60,728,612” refers to small molecules, nucleic acids, proteins, peptides or oligonucleotides that can bind to the location within the genomic DNA (e.g., chromosome 2 location 60,716,189-60,728,612) and represses mRNA or protein expression of BCL11A in a cell by at least 20% compared to the mRNA or protein level of BCL11A in a cell not treated with such an agent. In one embodiment, the agent “interferes with BCL11A interactions with BCL11A binding partners,” as that phrase is used herein.

As used herein, the term “small molecule” refers to a chemical agent including, but not limited to, peptides, peptidomimetics, amino acids, amino acid analogs, polynucleotides, polynucleotide analogs, aptamers, nucleotides, nucleotide analogs, organic or inorganic compounds (i.e., including heteroorganic and organometallic compounds) having a molecular weight less than about 10,000 grams per mole, organic or inorganic compounds having a molecular weight less than about 5,000 grams per mole, organic or inorganic compounds having a molecular weight less than about 1,000 grams per mole, organic or inorganic compounds having a molecular weight less than about 500 grams per mole, and salts, esters, and other pharmaceutically acceptable forms of such compounds.

A “nucleic acid”, as described herein, can be RNA or DNA, and can be single or double stranded, and can be selected, for example, from a group including: nucleic acid encoding a protein of interest, oligonucleotides, nucleic acid analogues, for example peptide-nucleic acid (PNA), pseudo-complementary PNA (pc-PNA), locked nucleic acid (LNA) etc. Such nucleic acid sequences include, for example, but are not limited to, nucleic acid sequence encoding proteins, for example that act as transcriptional repressors, antisense molecules, ribozymes, small inhibitory nucleic acid sequences, for example but are not limited to RNAi, shRNAi, siRNA, micro RNAi (mRNAi), antisense oligonucleotides etc.

By “interferes with BCL11A interactions with BCL11A binding partners” is meant that the amount of interaction of BCL11A with the BCL11A binding partner is at least 5% lower in populations treated with a BCL11A inhibitor, than a comparable, control population, wherein no BCL11A inhibitor is present. It is preferred that the amount of interaction of BCL11A with the BCL11A binding partner in a BCL11A-inhibitor treated population is at least 10% lower, at least 20% lower, at least 30% lower, at least 40% lower, at least 50% lower, at least 60% lower, at least 70% lower, at least 80% lower, at least 90% lower, at least 1-fold lower, at least 2-fold lower, at least 5-fold lower, at least 10 fold lower, at least 100 fold lower, at least 1000-fold lower, or more than a comparable control treated population in which no BCL11A inhibitor is added. At a minimum, BCL11A interaction can be assayed by determining the amount of BCL11A binding to the BCL11A binding partner using techniques standard in the art, including, but not limited to, mass spectrometry, immunoprecipitation, or gel filtration assays. Alternatively, or in addition, BCL11A activity can be assayed by measuring fetal hemoglobin expression at the mRNA or protein level following treatment with a candidate BCL11A inhibitor.

In one embodiment, BCL11A activity is the interaction of BCL11A with its binding partners: GATA-1, FOG-1, components of the NuRD complex, matrin-3, MTA2 and RBBP7. Accordingly, any antibody or fragment thereof, small molecule, chemical or compound that can block this interaction is considered an inhibitor of BCL11A activity.

As used herein, the term “genetic engineered cell” refers to a cell that comprises at least one genetic modification, as that term is used herein.

As used herein, the term “genetic modification” refers to a disruption at the genomic level resulting in a decrease in BCL11A expression or activity in a cell. Exemplary genetic modifications can include deletions, frame shift mutations, point mutations, exon removal, removal of one or more DNAse 1-hypersensitive sites (DHS) (e.g., 2, 3, 4 or more DHS regions), etc.

By “inhibits BCL11A expression” is meant that the amount of expression of BCL11A is at least 5% lower in a cell or cell population treated with a DNA-targeting endonuclease, than a comparable, control cell or cell population, wherein no DNA-targeting endonuclease is present. It is preferred that the percentage of BCL11A expression in a treated population is at least 10% lower, at least 20% lower, at least 30% lower, at least 40% lower, at least 50% lower, at least 60% lower, at least 70% lower, at least 80% lower, at least 90% lower, at least 1-fold lower, at least 2-fold lower, at least 5-fold lower, at least 10 fold lower, at least 100 fold lower, at least 1000-fold lower, or more than a comparable control treated population in which no DNA-targeting endonuclease is added.

By “inhibits BCL11A activity” is meant that the amount of functional activity of BCL11A is at least 5% lower in a cell or cell population treated with the methods described herein, than a comparable, control cell or population, wherein no DNA-targeting endonuclease is present. It is preferred that the percentage of BCL11A activity in a BCL11A-inhibitor treated population is at least 10% lower, at least 20% lower, at least 30% lower, at least 40% lower, at least 50% lower, at least 60% lower, at least 70% lower, at least 80% lower, at least 90% lower, at least 1-fold lower, at least 2-fold lower, at least 5-fold lower, at least 10 fold lower, at least 100 fold lower, at least 1000-fold lower, or more than a comparable control treated population in which no DNA-targeting endonuclease is added. At a minimum, BCL11A activity can be assayed by determining the amount of BCL11A expression at the protein or mRNA levels, using techniques standard in the art. Alternatively, or in addition, BCL11A activity can be determined using a reporter construct, wherein the reporter construct is sensitive to BCL11A activity. The γ-globin locus sequence is recognizable by the nucleic acid-binding motif of the BCL11A construct.

In one embodiment, as used herein, the term “DNA targeting endonuclease” refers to an endonuclease that generates a double-stranded break at a desired position in the genome (e.g., chromosome 2 location 60,716,189-60,728,612) without producing undesired off-target double-stranded breaks. The DNA targeting endonuclease can be a naturally occurring endonuclease (e.g., a bacterial meganuclease) or it can be artificially generated (e.g., engineered meganucleases, TALENs, or ZFNs, among others).

In another embodiment, as used herein, the term “DNA targeting endonuclease” refers to an endonuclease that generates a single-stranded break or a “nick” or break on one strand of the DNA phosphate sugar backbone at a desired position in the genome (e.g., chromosome 2 location 60,716,189-60,728,612) without producing undesired off-target DNA stranded breaks.

As used herein, the term “vector” refers to a nucleic acid molecule capable of transporting another nucleic acid to which it has been linked. One type of vector is a “plasmid”, which refers to a circular double stranded DNA loop into which additional nucleic acid segments can be ligated. Another type of vector is a viral vector, wherein additional nucleic acid segments can be ligated into the viral genome. Certain vectors are capable of autonomous replication in a host cell into which they are introduced (e.g., bacterial vectors having a bacterial origin of replication and episomal mammalian vectors). Other vectors (e.g., non-episomal mammalian vectors) are integrated into the genome of a host cell upon introduction into the host cell, and thereby are replicated along with the host genome. Moreover, certain vectors are capable of directing the expression of genes to which they are operatively linked. Such vectors are referred to herein as “recombinant expression vectors”, or more simply “expression vectors.” In general, expression vectors of utility in recombinant DNA techniques are often in the form of plasmids. In the present specification, “plasmid” and “vector” can be used interchangeably as the plasmid is the most commonly used form of vector. However, the methods and compositions described herein can include such other forms of expression vectors, such as viral vectors (e.g., replication defective retroviruses, lentiviruses, adenoviruses and adeno-associated viruses), which serve equivalent functions.

Within an expression vector, “operably linked” is intended to mean that the nucleotide sequence of interest is linked to the regulatory sequence(s) in a manner which allows for expression of the nucleotide sequence (e.g., in an in vitro transcription/translation system or in a target cell when the vector is introduced into the target cell). The term “regulatory sequence” is intended to include promoters, enhancers and other expression control elements (e.g., polyadenylation signals). Such regulatory sequences are described, for example, in Goeddel; Gene Expression Technology: Methods in Enzymology 185, Academic Press, San Diego, Calif. (1990). Regulatory sequences include those which direct constitutive expression of a nucleotide sequence in many types of host cell and those which direct expression of the nucleotide sequence only in certain host cells (e.g., tissue-specific regulatory sequences). Furthermore, the DNA-targeting endonuclease can be delivered by way of a vector comprising a regulatory sequence to direct synthesis of the DNA-targeting endonuclease at specific intervals, or over a specific time period. It will be appreciated by those skilled in the art that the design of the expression vector can depend on such factors as the choice of the target cell, the level of expression desired, and the like.

As used herein the term “cleaves” generally refers to the generation of a double-stranded break in the DNA genome at a desired location.

As used herein, the term “effective amount of a composition comprising at least a DNA-targeting endonuclease” refers to an amount of a DNA-targeting endonuclease that yields sufficient endonuclease activity to generate a double-stranded break in the desired location of the genome. In one embodiment, the effective amount of a DNA-targeting endonuclease generates a double-stranded break at the desired genetic locus in at least 20% of the cells in a population contacted with the composition (e.g., at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, at least 99%, or even 100% of the cells in the population comprise a genetic modification produced by the DNA-targeting endonuclease composition).

As used herein the term “increasing the fetal hemoglobin levels” in a cell indicates that fetal hemoglobin is at least 5% higher in populations treated with an agent that disrupts BCL11A mRNA or protein expression (e.g., a DNA-targeting endonuclease) by binding to genomic DNA at chromosome 2 location 60,716,189-60,728,612, than in a comparable, control population, wherein no agent is present. It is preferred that the percentage of fetal hemoglobin expression in a population treated with such an agent that binds the genomic DNA at chromosome 2 location 60,716,189-60,728,612 is at least 10% higher, at least 20% higher, at least 30% higher, at least 40% higher, at least 50% higher, at least 60% higher, at least 70% higher, at least 80% higher, at least 90% higher, at least 1-fold higher, at least 2-fold higher, at least 5-fold higher, at least 10 fold higher, at least 100 fold higher, at least 1000-fold higher, or more than a control treated population of comparable size and culture conditions. The term “control treated population” is used herein to describe a population of cells that has been treated with identical media, viral induction, nucleic acid sequences, temperature, confluency, flask size, pH, etc., with the exception of the addition of the agent that binds genomic DNA at chromosome 2 location 60,716,189-60,728,612. In one embodiment, any method known in the art can be used to measure an increase in fetal hemoglobin expression, e. g. Western Blot analysis of fetal γ-globin protein and quantifying mRNA of fetal γ-globin.

The term “isolated cell” as used herein refers to a cell that has been removed from an organism in which it was originally found, or a descendant of such a cell. Optionally the cell has been cultured in vitro, e.g., in the presence of other cells. Optionally the cell is later introduced into a second organism or re-introduced into the organism from which it (or the cell from which it is descended) was isolated.

The term “isolated population” with respect to an isolated population of cells as used herein refers to a population of cells that has been removed and separated from a mixed or heterogeneous population of cells. In some embodiments, an isolated population is a substantially pure population of cells as compared to the heterogeneous population from which the cells were isolated or enriched. In some embodiments, the isolated population is an isolated population of human hematopoietic progenitor cells, e.g., a substantially pure population of human hematopoietic progenitor cells as compared to a heterogeneous population of cells comprising human hematopoietic progenitor cells and cells from which the human hematopoietic progenitor cells were derived.

The term “substantially pure,” with respect to a particular cell population, refers to a population of cells that is at least about 75%, preferably at least about 85%, more preferably at least about 90%, and most preferably at least about 95% pure, with respect to the cells making up a total cell population. That is, the terms “substantially pure” or “essentially purified,” with regard to a population of hematopoietic progenitor cells, refers to a population of cells that contain fewer than about 20%, more preferably fewer than about 15%, 10%, 8%, 7%, most preferably fewer than about 5%, 4%, 3%, 2%, 1%, or less than 1%, of cells that are not hematopoietic progenitor cells as defined by the terms herein.

As used herein, the term “treating” includes reducing or alleviating at least one adverse effect or symptom of a condition, disease or disorder. For example, the term “treating” and “treatment” refers to administering to a subject an effective amount of a composition, e.g., an effective amount of a composition comprising a population of hematopoietic progenitor cells so that the subject has a reduction in at least one symptom of the disease or an improvement in the disease, for example, beneficial or desired clinical results. For purposes of this disclosure, beneficial or desired clinical results include, but are not limited to, alleviation of one or more symptoms, diminishment of extent of disease, disease stabilization (e.g., not worsening), delay or slowing of disease progression, amelioration or palliation of the disease state, and remission (whether partial or total), whether detectable or undetectable. In some embodiments, treating can refer to prolonging survival as compared to expected survival if not receiving treatment. Thus, one of skill in the art realizes that a treatment can improve the disease condition, but may not be a complete cure for the disease. In some embodiments, treatment can include prophylaxis. However, in alternative embodiments, treatment does not include prophylaxis.

The phrase “pharmaceutically acceptable” is employed herein to refer to those compounds, materials, compositions, and/or dosage forms which are, within the scope of sound medical judgment, suitable for use in contact with the tissues of human beings and animals without excessive toxicity, irritation, allergic response, or other problem or complication, commensurate with a reasonable benefit/risk ratio.

As used herein, the terms “pharmaceutically acceptable”, “physiologically tolerable” and grammatical variations thereof, as they refer to compositions, carriers, diluents and reagents, are used interchangeably and represent that the materials are capable of administration to or upon a mammal without the production of undesirable physiological effects such as nausea, dizziness, gastric upset and the like. A pharmaceutically acceptable carrier will not promote the raising of an immune response to an agent with which it is admixed, unless so desired. The preparation of a pharmacological composition that contains active ingredients dissolved or dispersed therein is well understood in the art and need not be limited based on formulation. Typically such compositions are prepared as injectable either as liquid solutions or suspensions, however, solid forms suitable for solution, or suspensions, in liquid prior to use can also be prepared. The preparation can also be emulsified or presented as a liposome composition. The active ingredient can be mixed with excipients which are pharmaceutically acceptable and compatible with the active ingredient and in amounts suitable for use in the therapeutic methods described herein. Suitable excipients are, for example, water, saline, dextrose, glycerol, ethanol or the like and combinations thereof. In addition, if desired, the composition can contain minor amounts of auxiliary substances such as wetting or emulsifying agents, pH buffering agents and the like which enhance the effectiveness of the active ingredient. The therapeutic composition of the present invention can include pharmaceutically acceptable salts of the components therein. Pharmaceutically acceptable salts include the acid addition salts (formed with the free amino groups of the polypeptide) that are formed with inorganic acids such as, for example, hydrochloric or phosphoric acids, or such organic acids as acetic, tartaric, mandelic and the like. Salts formed with the free carboxyl groups can also be derived from inorganic bases such as, for example, sodium, potassium, ammonium, calcium or ferric hydroxides, and such organic bases as isopropylamine, trimethylamine, 2-ethylamino ethanol, histidine, procaine and the like. Physiologically tolerable carriers are well known in the art. Exemplary liquid carriers are sterile aqueous solutions that contain no materials in addition to the active ingredients and water, or contain a buffer such as sodium phosphate at physiological pH value, physiological saline or both, such as phosphate-buffered saline. Still further, aqueous carriers can contain more than one buffer salt, as well as salts such as sodium and potassium chlorides, dextrose, polyethylene glycol and other solutes. Liquid compositions can also contain liquid phases in addition to and to the exclusion of water. Exemplary of such additional liquid phases are glycerin, vegetable oils such as cottonseed oil, and water-oil emulsions. The amount of an active agent used with the methods described herein that will be effective in the treatment of a particular disorder or condition will depend on the nature of the disorder or condition, and can be determined by standard clinical techniques.

As used herein, “prevention” or “preventing,” when used in reference to a disease, disorder or symptoms thereof, refers to a reduction in the likelihood that an individual will develop a disease or disorder, e.g., a hemoglobinopathy. The likelihood of developing a disease or disorder is reduced, for example, when an individual having one or more risk factors for a disease or disorder either fails to develop the disorder or develops such disease or disorder at a later time or with less severity, statistically speaking, relative to a population having the same risk factors and not receiving treatment as described herein. The failure to develop symptoms of a disease, or the development of reduced (e.g., by at least 10% on a clinically accepted scale for that disease or disorder) or delayed (e.g., by days, weeks, months or years) symptoms is considered effective prevention.

In connection with contacting a cell with a DNA-targeting endonuclease to decrease BCL11A expression, the phrase “increasing fetal hemoglobin levels in a cell” indicates that fetal hemoglobin in a cell or population of cells is at least 5% higher in the cell or population of cells treated with the DNA-targeting endonuclease, than a comparable, control population, wherein no DNA-targeting endonuclease is present. It is preferred that the fetal hemoglobin expression in a DNA-targeting endonuclease treated cell is at least 10% higher, at least 20% higher, at least 30% higher, at least 40% higher, at least 50% higher, at least 60% higher, at least 70% higher, at least 80% higher, at least 90% higher, at least 1-fold higher, at least 2-fold higher, at least 5-fold higher, at least 10 fold higher, at least 100 fold higher, at least 1000-fold higher, or more than a comparable control treated population. The term “control treated population” is used herein to describe a population of cells that has been treated with identical media, viral induction, nucleic acid sequences, temperature, confluency, flask size, pH, etc., with the exception of the addition of the BCL11A inhibitor.

The term “mammal” is intended to encompass a singular “mammal” and plural “mammals,” and includes, but is not limited to humans; primates such as apes, monkeys, orangutans, and chimpanzees; canids such as dogs and wolves; felids such as cats, lions, and tigers; equids such as horses, donkeys, and zebras; food animals such as cows, pigs, and sheep; ungulates such as deer and giraffes; rodents such as mice, rats, hamsters and guinea pigs; and bears. In some preferred embodiments, a mammal is a human.

Accordingly, in one embodiment, the mammal has been diagnosed with a hemoglobinopathy. In a further embodiment, the hemoglobinopathy is a β-hemoglobinopathy. In one preferred embodiment, the hemoglobinopathy is a sickle cell disease. As used herein, “sickle cell disease” can be sickle cell anemia, sickle-hemoglobin C disease (HbSC), sickle beta-plus-thalassaemia (HbS/β+), or sickle beta-zero-thalassaemia (HbS/β0). In another preferred embodiment, the hemoglobinopathy is a β-thalassemia.

As used herein, the term “hemoglobinopathy” means any defect in the structure or function of any hemoglobin of an individual, and includes defects in the primary, secondary, tertiary or quaternary structure of hemoglobin caused by any mutation, such as deletion mutations or substitution mutations in the coding regions of the β-globin gene, or mutations in, or deletions of, the promoters or enhancers of such genes that cause a reduction in the amount of hemoglobin produced as compared to a normal or standard condition. The term further includes any decrease in the amount or effectiveness of hemoglobin, whether normal or abnormal, caused by external factors such as disease, chemotherapy, toxins, poisons, or the like.

In one embodiment, the term “effective amount”, as used herein, refers to the amount of a cell composition that is safe and sufficient to treat, lesson the likelihood of, or delay the development of a hemoglobinopathy. The amount can thus cure or result in amelioration of the symptoms of the hemoglobinopathy, slow the course of hemoglobinopathy disease progression, slow or inhibit a symptom of a hemoglobinopathy, slow or inhibit the establishment of secondary symptoms of a hemoglobinopathy or inhibit the development of a secondary symptom of a hemoglobinopathy. The effective amount for the treatment of the hemoglobinopathy depends on the type of hemoglobinopathy to be treated, the severity of the symptoms, the subject being treated, the age and general condition of the subject, the mode of administration and so forth. Thus, it is not possible or prudent to specify an exact “effective amount”. However, for any given case, an appropriate “effective amount” can be determined by one of ordinary skill in the art using only routine experimentation.

As used herein the term “comprising” or “comprises” is used in reference to compositions, methods, and respective component(s) thereof, that are essential to the invention, yet open to the inclusion of unspecified elements, whether essential or not.

As used herein the term “consisting essentially of” refers to those elements required for a given embodiment. The term permits the presence of additional elements that do not materially affect the basic and novel or functional characteristic(s) of that embodiment of the invention.

The term “consisting of” refers to compositions, methods, and respective components thereof as described herein, which are exclusive of any element not recited in that description of the embodiment.

As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise. Thus for example, references to “the method” includes one or more methods, and/or steps of the type described herein and/or which will become apparent to those persons skilled in the art upon reading this disclosure and so forth. It is understood that the foregoing detailed description and the following examples are illustrative only and are not to be taken as limitations upon the scope of the invention. Various changes and modifications to the disclosed embodiments, which will be apparent to those of skill in the art, may be made without departing from the spirit and scope of the present invention. Further, all patents, patent applications, and publications identified are expressly incorporated herein by reference for the purpose of describing and disclosing, for example, the methodologies described in such publications that might be used in connection with the present invention. These publications are provided solely for their disclosure prior to the filing date of the present application. Nothing in this regard should be construed as an admission that the inventors are not entitled to antedate such disclosure by virtue of prior invention or for any other reason. All statements as to the date or representation as to the contents of these documents are based on the information available to the applicants and do not constitute any admission as to the correctness of the dates or contents of these documents.

Hemoglobinopathies

Fetal hemoglobin (HbF) is a tetramer of two adult α-globin polypeptides and two fetal β-like γ-globin polypeptides. During gestation, the duplicated γ-globin genes constitute the predominant genes transcribed from the β-globin locus. Following birth, γ-globin becomes progressively replaced by adult β-globin, a process referred to as the “fetal switch” (3). The molecular mechanisms underlying this switch have remained largely undefined and have been a subject of intense research. The developmental switch from production of predominantly fetal hemoglobin or HbF (α2γ2) to production of adult hemoglobin or HbA (α2γ2) begins at about 28 to 34 weeks of gestation and continues shortly after birth at which point HbA becomes predominant. This switch results primarily from decreased transcription of the gamma-globin genes and increased transcription of beta-globin genes. On average, the blood of a normal adult contains only about 2% HbF, though residual HbF levels have a variance of over 20 fold in healthy adults (Atweh, Semin. Hematol. 38(4):367-73 (2001)).

Hemoglobinopathies encompass a number of anemias of genetic origin in which there is a decreased production and/or increased destruction (hemolysis) of red blood cells (RBCs). These disorders also include genetic defects that result in the production of abnormal hemoglobins with a concomitant impaired ability to maintain oxygen concentration. Some such disorders involve the failure to produce normal β-globin in sufficient amounts, while others involve the failure to produce normal β-globin entirely. These disorders specifically associated with the β-globin protein are referred to generally as β-hemoglobinopathies. For example, β-thalassemias result from a partial or complete defect in the expression of the β-globin gene, leading to deficient or absent HbA. Sickle cell anemia results from a point mutation in the β-globin structural gene, leading to the production of an abnormal (sickled) hemoglobin (HbS). HbS RBCs are more fragile than normal RBCs and undergo hemolysis more readily, leading eventually to anemia (Atweh, Semin. Hematol. 38(4):367-73 (2001)). Moreover, the presence of a BCL11A genetic variant, HBS1L-MYB variation, ameliorates the clinical severity in beta-thalassemia. This variant has been shown to be associated with HbF levels. It has been shown that there is an odds ratio of 5 for having a less severe form of beta-thalassemia with the high-HbF variant (Galanello S. et al., 2009, Blood, in press).

The search for treatment aimed at reduction of globin chain imbalance in patients with β-hemoglobinopathies has focused on the pharmacologic manipulation of fetal hemoglobin (α2γ2; HbF). The important therapeutic potential of such approaches is suggested by observations of the mild phenotype of individuals with co-inheritance of both homozygous β-thalassemia and hereditary persistence of fetal hemoglobin (HPFH), as well as by those patients with homozygous β-thalassemia who synthesize no adult hemoglobin, but in whom a reduced requirement for transfusions is observed in the presence of increased concentrations of fetal hemoglobin. Furthermore, it has been observed that certain populations of adult patients with β chain abnormalities have higher than normal levels of fetal hemoglobin (HbF), and have been observed to have a milder clinical course of disease than patients with normal adult levels of HbF. For example, a group of Saudi Arabian sickle-cell anemia patients who express 20-30% HbF have only mild clinical manifestations of the disease (Pembrey, et al., Br. J. Haematol. 40: 415-429 (1978)). It is now accepted that β-hemoglobinopathies, such as sickle cell anemia and the β-thalassemias, are ameliorated by increased HbF production. (Reviewed in Jane and Cunningham Br. J. Haematol. 102: 415-422 (1998) and Bunn, N. Engl. J. Med. 328: 129-131 (1993)).

While the molecular mechanisms controlling the in vivo developmental switch from γ- to β-globin gene expression are currently unknown, there is accumulating evidence that external factors can influence γ-globin gene expression. The first group of compounds discovered having HbF reactivation activity were cytotoxic drugs. The ability to cause de novo synthesis of HbF by pharmacological manipulation was first shown using 5-azacytidine in experimental animals (DeSimone, Proc Natl Acad Sci USA. 79(14):4428-31 (1982)). Subsequent studies confirmed the ability of 5-azacytidine to increase HbF in patients with β-thalassemia and sickle cell disease (Ley, et al., N. Engl. J. Medicine, 307: 1469-1475 (1982), and Ley, et al., Blood 62: 370-380 (1983)). Additional experiments demonstrated that baboons treated with cytotoxic doses of arabinosylcytosine (ara-C) responded with striking elevations of F-reticulocytes (Papayannopoulou et al., Science. 224(4649):617-9 (1984)), and that treatment with hydroxyurea led to induction of γ-globin in monkeys or baboons (Letvin et. al., N Engl J Med. 310(14):869-73 (1984)).

The second group of compounds investigated for the ability to cause HbF reactivation activity was short chain fatty acids. The initial observation in fetal cord blood progenitor cells led to the discovery that γ-aminobutyric acid can act as a fetal hemoglobin inducer (Perrine et al., Biochem Biophys Res Commun.148(2):694-700 (1987)). Subsequent studies showed that butyrate stimulated globin production in adult baboons (Constantoulakis et al., Blood. Dec; 72(6):1961-7 (1988)), and it induced γ-globin in erythroid progenitors in adult animals or patients with sickle cell anemia (Perrine et al., Blood. 74(1):454-9 (1989)). Derivatives of short chain fatty acids such as phenylbutyrate (Dover et al., Br J Haematol. 88(3):555-61 (1994)) and valproic acid (Liakopoulou et al., 1: Blood. 186(8):3227-35 (1995)) also have been shown to induce HbF in vivo. Given the large number of short chain fatty acid analogs or derivatives of this family, there are a number of potential compounds of this family more potent than butyrate. Phenylacetic and phenylalkyl acids (Torkelson et al., Blood Cells Mol Dis. 22(2):150-8. (1996)), which were discovered during subsequent studies, were considered potential HbF inducers as they belonged to this family of compounds. Presently, however, the use of butyrate or its analogs in sickle cell anemia and β-thalassemia remains experimental and cannot be recommended for treatment outside of clinical trials.

Clinical trials aimed at reactivation of fetal hemoglobin synthesis in sickle cell anemia and β-thalassemia have included short term and long term administration of such compounds as 5-azacytidine, hydroxyurea, recombinant human erythropoietin, and butyric acid analogs, as well as combinations of these agents. Following these studies, hydroxyurea was used for induction of HbF in humans and later became the first and only drug approved by the Food and Drug Administration (FDA) for the treatment of hemoglobinopathies. However, varying drawbacks have contraindicated the long term use of such agents or therapies, including unwanted side effects and variability in patient responses. For example, while hydroxyurea stimulates HbF production and has been shown to clinically reduce sickling crisis, it is potentially limited by myelotoxicity and the risk of carcinogenesis. Potential long term carcinogenicity would also exist in 5-azacytidine-based therapies. Erythropoietin-based therapies have not proved consistent among a range of patient populations. The short half-lives of butyric acid in vivo have been viewed as a potential obstacle in adapting these compounds for use in therapeutic interventions. Furthermore, very high dosages of butyric acid are necessary for inducing γ-globin gene expression, requiring catheritization for continuous infusion of the compound. Moreover, these high dosages of butyric acid can be associated with neurotoxicity and multiorgan damage (Blau, et al., Blood 81: 529-537 (1993)). While even minimal increases in HbF levels are helpful in sickle cell disease, β-thalassemias require a much higher increase that is not reliably, or safely, achieved by any of the currently used agents (Olivieri, Seminars in Hematology 33: 24-42 (1996)).

Identifying natural regulators of HbF induction and production could provide a means to devise therapeutic interventions that overcome the various drawbacks of the compounds described above. Recent genome-wide association studies have yielded insights into the genetic basis of numerous complex diseases and traits (McCarthy et al., Nat Rev Genet 9, 356 (2008) and Manolio et. al. J Clin Invest 118, 1590 (2008)). However, in the vast majority of instances, the functional link between a genetic association and the underlying pathophysiology remains to be uncovered. The level of fetal hemoglobin (HbF) is inherited as a quantitative trait and clinically important, given its above-mentioned and well-characterized role in ameliorating the severity of the principal β-hemoglobinopathies, sickle cell disease and β-thalassemia (Nathan et. al., Nathan and Oski's hematology of infancy and childhood ed. 6th, pp. 2 v. (xiv, 1864, xli p.) 2003)). Two genome-wide association studies have identified three major loci containing a set of five common single nucleotide polymorphisms (SNPs) that account for ˜20% of the variation in HbF levels (Lettre et al., Proc Natl Acad Sci USA (2008); Uda et al., Proc Natl Acad Sci USA 105, 1620 (2008); Menzel et al., Nat Genet 39, 1197 (2007)). Moreover, several of these variants appear to predict the clinical severity of sickle cell disease (Lettre et al., Proc Natl Acad Sci USA (2008)) and at least one of these SNPs may also affect clinical outcome in β-thalassemia (Uda et al., Proc Natl Acad Sci USA 105, 1620 (2008)). The SNP with the largest effect size, explaining over 10% of the variation in HbF, is located in the second intron of a gene on chromosome 2, BCL11A. Whereas BCL11A, a C2H2-type zinc finger transcription factor, has been investigated for its role in lymphocyte development (Liu et al., Nat Immunol 4, 525 (2003) and Liu et al., Mol Cancer 5, 18 (2006)), its role in red blood cell production or globin gene regulation has not been previously assessed.

At the onset of the recombinant DNA era, studies of globin gene structure provided a strong molecular foundation for interrogating the fetal globin switch. Considerable effort has focused on delineating the cis-elements within the β-globin locus necessary for proper regulation of the genes within the β-like globin cluster. These studies relied on naturally occurring mutations and deletions that dramatically influence HbF levels in adults, and have been complemented by generation of transgenic mice harboring portions of the cluster (Nathan et. al., Nathan and Oski's hematology of infancy and childhood ed. 6th, pp. 2 v. (xiv, 1864, xli p.) 2003) and G. Stamatoyannopoulos, Exp Hematol 33, 259 (2005)). Although the precise cis-elements required for globin switching remain ill-defined, findings in transgenic mice have strongly indicated that the γ-globin genes are autonomously silenced in the adult stage, a finding that is most compatible with the absence of fetal-stage specific activators or the presence of a stage-specific repressor. The results of recent genetic association studies provide candidate genes to interrogate for their involvement in control of the γ-globin genes, such as BCL11A.

Hematopoietic Progenitor Cells

In one embodiment, the hematopoietic progenitor cell is contacted ex vivo or in vitro. In a specific embodiment, the cell being contacted is a cell of the erythroid lineage. In one embodiment, the cell composition comprises cells having decreased BCL11A expression.

“Hematopoietic progenitor cell” as the term is used herein, refers to cells of a stem cell lineage that give rise to all the blood cell types including the myeloid (monocytes and macrophages, neutrophils, basophils, eosinophils, erythrocytes, megakaryocytes/platelets, dendritic cells), and the lymphoid lineages (T-cells, B-cells, NK-cells). A “cell of the erythroid lineage” indicates that the cell being contacted is a cell that undergoes erythropoeisis such that upon final differentiation it forms an erythrocyte or red blood cell (RBC). Such cells belong to one of three lineages, erythroid, lymphoid, and myeloid, originating from bone marrow haematopoietic progenitor cells. Upon exposure to specific growth factors and other components of the haematopoietic microenvironment, haematopoietic progenitor cells can mature through a series of intermediate differentiation cellular types, all intermediates of the erythroid lineage, into RBCs. Thus, cells of the “erythroid lineage”, as the term is used herein, comprise hematopoietic progenitor cells, rubriblasts, prorubricytes, erythroblasts, metarubricytes, reticulocytes, and erythrocytes.

In some embodiment, the hematopoietic progenitor cell has at least one of the cell surface marker characteristic of hematopoietic progenitor cells: CD34+, CD59+, Thy1/CD90+,CD381o/−, and C-kit/CD117+. Preferably, the hematopoietic progenitor cells have several of these markers.

In some embodiments, the hematopoietic progenitor cells of the erythroid lineage have the cell surface marker characteristic of the erythroid lineage: CD71 and Ter119.

Stem cells, such as hematopoietic progenitor cells, are capable of proliferation and giving rise to more progenitor cells having the ability to generate a large number of mother cells that can in turn give rise to differentiated or differentiable daughter cells. The daughter cells themselves can be induced to proliferate and produce progeny that subsequently differentiate into one or more mature cell types, while also retaining one or more cells with parental developmental potential. The term “stem cell” refers then, to a cell with the capacity or potential, under particular circumstances, to differentiate to a more specialized or differentiated phenotype, and which retains the capacity, under certain circumstances, to proliferate without substantially differentiating. In one embodiment, the term progenitor or stem cell refers to a generalized mother cell whose descendants (progeny) specialize, often in different directions, by differentiation, e.g., by acquiring completely individual characters, as occurs in progressive diversification of embryonic cells and tissues. Cellular differentiation is a complex process typically occurring through many cell divisions. A differentiated cell may derive from a multipotent cell which itself is derived from a multipotent cell, and so on. While each of these multipotent cells may be considered stem cells, the range of cell types each can give rise to may vary considerably. Some differentiated cells also have the capacity to give rise to cells of greater developmental potential. Such capacity may be natural or may be induced artificially upon treatment with various factors. In many biological instances, stem cells are also “multipotent” because they can produce progeny of more than one distinct cell type, but this is not required for “stem-ness.” Self-renewal is the other classical part of the stem cell definition, and it is essential as used in this document. In theory, self-renewal can occur by either of two major mechanisms. Stem cells may divide asymmetrically, with one daughter retaining the stem state and the other daughter expressing some distinct other specific function and phenotype. Alternatively, some of the stem cells in a population can divide symmetrically into two stems, thus maintaining some stem cells in the population as a whole, while other cells in the population give rise to differentiated progeny only. Generally, “progenitor cells” have a cellular phenotype that is more primitive (i.e., is at an earlier step along a developmental pathway or progression than is a fully differentiated cell). Often, progenitor cells also have significant or very high proliferative potential. Progenitor cells can give rise to multiple distinct differentiated cell types or to a single differentiated cell type, depending on the developmental pathway and on the environment in which the cells develop and differentiate.

In the context of cell ontogeny, the adjective “differentiated”, or “differentiating” is a relative term. A “differentiated cell” is a cell that has progressed further down the developmental pathway than the cell it is being compared with. Thus, stem cells can differentiate to lineage-restricted precursor cells (such as a hematopoietic progenitor cell), which in turn can differentiate into other types of precursor cells further down the pathway (such as an erthyrocyte precursor), and then to an end-stage differentiated cell, such as an erthyrocyte, which plays a characteristic role in a certain tissue type, and may or may not retain the capacity to proliferate further.

Induced Pluripotent Stem Cells

In some embodiments, the genetic engineered human cells described herein are derived from isolated pluripotent stem cells. An advantage of using iPSCs is that the cells can be derived from the same subject to which the progenitor cells are to be administered. That is, a somatic cell can be obtained from a subject, reprogrammed to an induced pluripotent stem cell, and then re-differentiated into a hematopoietic progenitor cell to be administered to the subject (e.g., autologous cells). Since the progenitors are essentially derived from an autologous source, the risk of engraftment rejection or allergic responses is reduced compared to the use of cells from another subject or group of subjects. In some embodiments, the hematopoeitic progenitors are derived from non-autologous sources. In addition, the use of iPSCs negates the need for cells obtained from an embryonic source. Thus, in one embodiment, the stem cells used in the disclosed methods are not embryonic stem cells.

Although differentiation is generally irreversible under physiological contexts, several methods have been recently developed to reprogram somatic cells to induced pluripotent stem cells. Exemplary methods are known to those of skill in the art and are described briefly herein below.

As used herein, the term “reprogramming” refers to a process that alters or reverses the differentiation state of a differentiated cell (e.g., a somatic cell). Stated another way, reprogramming refers to a process of driving the differentiation of a cell backwards to a more undifferentiated or more primitive type of cell. It should be noted that placing many primary cells in culture can lead to some loss of fully differentiated characteristics. Thus, simply culturing such cells included in the term differentiated cells does not render these cells non-differentiated cells (e.g., undifferentiated cells) or pluripotent cells. The transition of a differentiated cell to pluripotency requires a reprogramming stimulus beyond the stimuli that lead to partial loss of differentiated character in culture. Reprogrammed cells also have the characteristic of the capacity of extended passaging without loss of growth potential, relative to primary cell parents, which generally have capacity for only a limited number of divisions in culture.

The cell to be reprogrammed can be either partially or terminally differentiated prior to reprogramming. In some embodiments, reprogramming encompasses complete reversion of the differentiation state of a differentiated cell (e.g., a somatic cell) to a pluripotent state or a multipotent state. In some embodiments, reprogramming encompasses complete or partial reversion of the differentiation state of a differentiated cell (e.g., a somatic cell) to an undifferentiated cell (e.g., an embryonic-like cell). Reprogramming can result in expression of particular genes by the cells, the expression of which further contributes to reprogramming. In certain embodiments described herein, reprogramming of a differentiated cell (e.g., a somatic cell) causes the differentiated cell to assume an undifferentiated state (e.g., is an undifferentiated cell). The resulting cells are referred to as “reprogrammed cells,” or “induced pluripotent stem cells (iPSCs or iPS cells).”

Reprogramming can involve alteration, e.g., reversal, of at least some of the heritable patterns of nucleic acid modification (e.g., methylation), chromatin condensation, epigenetic changes, genomic imprinting, etc., that occur during cellular differentiation. Reprogramming is distinct from simply maintaining the existing undifferentiated state of a cell that is already pluripotent or maintaining the existing less than fully differentiated state of a cell that is already a multipotent cell (e.g., a hematopoietic stem cell). Reprogramming is also distinct from promoting the self-renewal or proliferation of cells that are already pluripotent or multipotent, although the compositions and methods described herein can also be of use for such purposes, in some embodiments.

The specific approach or method used to generate pluripotent stem cells from somatic cells (broadly referred to as “reprogramming”) is not critical to the claimed invention. Thus, any method that re-programs a somatic cell to the pluripotent phenotype would be appropriate for use in the methods described herein.

Reprogramming methodologies for generating pluripotent cells using defined combinations of transcription factors have been described induced pluripotent stem cells. Yamanaka and Takahashi converted mouse somatic cells to ES cell-like cells with expanded developmental potential by the direct transduction of Oct4, Sox2, Klf4, and c-Myc (Takahashi and Yamanaka, 2006). iPSCs resemble ES cells as they restore the pluripotency-associated transcriptional circuitry and muc of the epigenetic landscape. In addition, mouse iPSCs satisfy all the standard assays for pluripotency: specifically, in vitro differentiation into cell types of the three germ layers, teratoma formation, contribution to chimeras, germline transmission (Maherali and Hochedlinger, 2008), and tetraploid complementation (Woltjen et al., 2009).

Subsequent studies have shown that human iPS cells can be obtained using similar transduction methods (Lowry et al., 2008; Park et al., 2008; Takahashi et al., 2007; Yu et al., 2007b), and the transcription factor trio, OCT4, SOX2, and NANOG, has been established as the core set of transcription factors that govern pluripotency (Jaenisch and Young, 2008). The production of iPS cells can be achieved by the introduction of nucleic acid sequences encoding stem cell-associated genes into an adult, somatic cell, historically using viral vectors.

iPS cells can be generated or derived from terminally differentiated somatic cells, as well as from adult stem cells, or somatic stem cells. That is, a non-pluripotent progenitor cell can be rendered pluripotent or multipotent by reprogramming. In such instances, it may not be necessary to include as many reprogramming factors as required to reprogram a terminally differentiated cell. Further, reprogramming can be induced by the non-viral introduction of reprogramming factors, e.g., by introducing the proteins themselves, or by introducing nucleic acids that encode the reprogramming factors, or by introducing messenger RNAs that upon translation produce the reprogramming factors (see e.g., Warren et al., Cell Stem Cell, 2010 Nov. 5; 7(5):618-30). Reprogramming can be achieved by introducing a combination of nucleic acids encoding stem cell-associated genes including, for example Oct-4 (also known as Oct-3/4 or Pouf51), Sox1, Sox2, Sox3, Sox 15, Sox 18, NANOG, Klf1, Klf2, Klf4, Klf5, NR5A2, c-Myc, 1-Myc, n-Myc, Rem2, Tert, and LIN28. In one embodiment, reprogramming using the methods and compositions described herein can further comprise introducing one or more of Oct-3/4, a member of the Sox family, a member of the Klf family, and a member of the Myc family to a somatic cell. In one embodiment, the methods and compositions described herein further comprise introducing one or more of each of Oct 4, Sox2, Nanog, c-MYC and Klf4 for reprogramming. As noted above, the exact method used for reprogramming is not necessarily critical to the methods and compositions described herein. However, where cells differentiated from the reprogrammed cells are to be used in, e.g., human therapy, in one embodiment the reprogramming is not effected by a method that alters the genome. Thus, in such embodiments, reprogramming is achieved, e.g., without the use of viral or plasmid vectors.

The efficiency of reprogramming (i.e., the number of reprogrammed cells) derived from a population of starting cells can be enhanced by the addition of various small molecules as shown by Shi, Y., et al (2008) Cell-Stem Cell 2:525-528, Huangfu, D., et al (2008) Nature Biotechnology 26(7):795-797, and Marson, A., et al (2008) Cell-Stem Cell 3:132-135. Thus, an agent or combination of agents that enhance the efficiency or rate of induced pluripotent stem cell production can be used in the production of patient-specific or disease-specific iPSCs. Some non-limiting examples of agents that enhance reprogramming efficiency include soluble Wnt, Wnt conditioned media, BIX-01294 (a G9a histone methyltransferase), PD0325901 (a MEK inhibitor), DNA methyltransferase inhibitors, histone deacetylase (HDAC) inhibitors, valproic acid, 5′-azacytidine, dexamethasone, suberoylanilide hydroxamic acid (SAHA), vitamin C, and trichostatin (TSA), among others.

Other non-limiting examples of reprogramming enhancing agents include: Suberoylanilide Hydroxamic Acid (SAHA (e.g., MK0683, vorinostat) and other hydroxamic acids), BML-210, Depudecin (e.g., (−)-Depudecin), HC Toxin, Nullscript (4-(1,3-Dioxo-1H,3H-benzo[de]isoquinolin-2-yl)-N-hydroxybutanamide), Phenylbutyrate (e.g., sodium phenylbutyrate) and Valproic Acid ((VPA) and other short chain fatty acids), Scriptaid, Suramin Sodium, Trichostatin A (TSA), APHA Compound 8, Apicidin, Sodium Butyrate, pivaloyloxymethyl butyrate (Pivanex, AN-9), Trapoxin B, Chlamydocin, Depsipeptide (also known as FR901228 or FK228), benzamides (e.g., CI-994 (e.g., N-acetyl dinaline) and MS-27-275), MGCD0103, NVP-LAQ-824, CBHA (m-carboxycinnaminic acid bishydroxamic acid), JNJ16241199, Tubacin, A-161906, proxamide, oxamflatin, 3-Cl-UCHA (e.g., 6-(3-chlorophenylureido)caproic hydroxamic acid), AOE (2-amino-8-oxo-9,10-epoxydecanoic acid), CHAP31 and CHAP 50. Other reprogramming enhancing agents include, for example, dominant negative forms of the HDACs (e.g., catalytically inactive forms), siRNA inhibitors of the HDACs, and antibodies that specifically bind to the HDACs. Such inhibitors are available, e.g., from BIOMOL International, Fukasawa, Merck Biosciences, Novartis, Gloucester Pharmaceuticals, Aton Pharma, Titan Pharmaceuticals, Schering A G, Pharmion, MethylGene, and Sigma Aldrich.

To confirm the induction of pluripotent stem cells for use with the methods described herein, isolated clones can be tested for the expression of a stem cell marker. Such expression in a cell derived from a somatic cell identifies the cells as induced pluripotent stem cells. Stem cell markers can be selected from the non-limiting group including SSEA3, SSEA4, CD9, Nanog, Fbx15, Ecat1, Esg1, Eras, Gdf3, Fgf4, Cripto, Dax1, Zpf296, Slc2a3, Rex1, Utf1, and Nat1. In one embodiment, a cell that expresses Oct4 or Nanog is identified as pluripotent. Methods for detecting the expression of such markers can include, for example, RT-PCR and immunological methods that detect the presence of the encoded polypeptides, such as Western blots or flow cytometric analyses. In some embodiments, detection does not involve only RT-PCR, but also includes detection of protein markers. Intracellular markers may be best identified via RT-PCR, while cell surface markers are readily identified, e.g., by immunocytochemistry.

The pluripotent stem cell character of isolated cells can be confirmed by tests evaluating the ability of the iPSCs to differentiate to cells of each of the three germ layers. As one example, teratoma formation in nude mice can be used to evaluate the pluripotent character of the isolated clones. The cells are introduced to nude mice and histology and/or immunohistochemistry is performed on a tumor arising from the cells. The growth of a tumor comprising cells from all three germ layers, for example, further indicates that the cells are pluripotent stem cells.

Somatic Cells for Reprogramming

Somatic cells, as that term is used herein, refer to any cells forming the body of an organism, excluding germline cells. Every cell type in the mammalian body—apart from the sperm and ova, the cells from which they are made (gametocytes) and undifferentiated stem cells—is a differentiated somatic cell. For example, internal organs, skin, bones, blood, and connective tissue are all made up of differentiated somatic cells.

Additional somatic cell types for use with the compositions and methods described herein include: a fibroblast (e.g., a primary fibroblast), a muscle cell (e.g., a myocyte), a cumulus cell, a neural cell, a mammary cell, an hepatocyte and a pancreatic islet cell. In some embodiments, the somatic cell is a primary cell line or is the progeny of a primary or secondary cell line. In some embodiments, the somatic cell is obtained from a human sample, e.g., a hair follicle, a blood sample, a biopsy (e.g., a skin biopsy or an adipose biopsy), a swab sample (e.g., an oral swab sample), and is thus a human somatic cell.

Some non-limiting examples of differentiated somatic cells include, but are not limited to, epithelial, endothelial, neuronal, adipose, cardiac, skeletal muscle, immune cells, hepatic, splenic, lung, circulating blood cells, gastrointestinal, renal, bone marrow, and pancreatic cells. In some embodiments, a somatic cell can be a primary cell isolated from any somatic tissue including, but not limited to brain, liver, gut, stomach, intestine, fat, muscle, uterus, skin, spleen, endocrine organ, bone, etc. Further, the somatic cell can be from any mammalian species, with non-limiting examples including a murine, bovine, simian, porcine, equine, ovine, or human cell. In some embodiments, the somatic cell is a human somatic cell.

When reprogrammed cells are used for generation of hematopoietic progenitor cells to be used in the therapeutic treatment of disease, it is desirable, but not required, to use somatic cells isolated from the patient being treated. For example, somatic cells involved in diseases, and somatic cells participating in therapeutic treatment of diseases and the like can be used. In some embodiments, a method for selecting the reprogrammed cells from a heterogeneous population comprising reprogrammed cells and somatic cells they were derived or generated from can be performed by any known means. For example, a drug resistance gene or the like, such as a selectable marker gene can be used to isolate the reprogrammed cells using the selectable marker as an index.

Reprogrammed somatic cells as disclosed herein can express any number of pluripotent cell markers, including: alkaline phosphatase (AP); ABCG2; stage specific embryonic antigen-1 (SSEA-1); SSEA-3; SSEA-4; TRA-1-60; TRA-1-81; Tra-2-49/6E; ERas/ECATS, E-cadherin; β-III-tubulin; α-smooth muscle actin (α-SMA); fibroblast growth factor 4 (Fgf4), Cripto, Dax1; zinc finger protein 296 (Zfp296); N-acetyltransferase-1 (Nat1); (ES cell associated transcript 1 (ECAT1); ESG1/DPPAS/ECAT2; ECAT3; ECAT6; ECAT7; ECAT8; ECAT9; ECAT10; ECAT15-1; ECAT15-2; Fthl17; Sal14; undifferentiated embryonic cell transcription factor (Utfl); Rex1; p53; G3PDH; telomerase, including TERT; silent X chromosome genes; Dnmt3a; Dnmt3b; TRIM28; F-box containing protein 15 (Fbx15); Nanog/ECAT4; Oct3/4; Sox2; Klf4; c-Myc; Esrrb; TDGF1; GABRB3; Zfp42, FoxD3; GDF3; CYP25A1; developmental pluripotency-associated 2 (DPPA2); T-cell lymphoma breakpoint 1 (Tcl1); DPPA3/Stella; DPPA4; other general markers for pluripotency, etc. Other markers can include Dnmt3L; Sox15; Stat3; Grb2; β-catenin, and Bmi1. Such cells can also be characterized by the down-regulation of markers characteristic of the somatic cell from which the induced pluripotent stem cell is derived.

Genome Editing and DNA-targeting Endonucleases

As used herein, the term “genome editing” refers to a reverse genetics method using artificially engineered nucleases to cut and create specific double-stranded breaks at a desired location(s) in the genome, which are then repaired by cellular endogenous processes such as, homologous recombination (HR), homology directed repair (HDR) and non-homologous end-joining (NHEJ). NHEJ directly joins the DNA ends in a double-stranded break, while HDR utilizes a homologous sequence as a template for regenerating the missing DNA sequence at the break point.

Genome editing cannot be performed using traditional restriction endonucleases since most restriction enzymes recognize a few base pairs on the DNA as their target and the probability is very high that the recognized base pair combination will be found in many locations across the genome resulting in multiple cuts (i.e., not limited to a desired location). To overcome this challenge and create site-specific double-stranded breaks, several distinct classes of nucleases have been discovered and bioengineered to date. These are the meganucleases, Zinc finger nucleases (ZFNs), Cas9/CRISPR system, and transcription-activator like effector nucleases (TALENs).

Meganucleases are commonly grouped into four families: the LAGLIDADG (SEQ ID NO: 1) family, the GIY-YIG family, the His-Cys box family and the HNH family. These families are characterized by structural motifs, which affect catalytic activity and recognition sequence. For instance, members of the LAGLIDADG (SEQ ID NO: 1) family are characterized by having either one or two copies of the conserved LAGLIDADG (SEQ ID NO: 1) motif (see Chevalier et al. (2001), Nucleic Acids Res. 29(18): 3757-3774). The LAGLIDADG (SEQ ID NO: 1) meganucleases with a single copy of the LAGLIDADG (SEQ ID NO: 1) motif form homodimers, whereas members with two copies of the LAGLIDADG (SEQ ID NO: 1) are found as monomers. Similarly, the GIY-YIG family members have a GIY-YIG module, which is 70-100 residues long and includes four or five conserved sequence motifs with four invariant residues, two of which are required for activity (see Van Roey et al. (2002), Nature Struct. Biol. 9: 806-811). The His-Cys box meganucleases are characterized by a highly conserved series of histidines and cysteines over a region encompassing several hundred amino acid residues (see Chevalier et al. (2001), Nucleic Acids Res. 29(18): 3757-3774). In the case of the NHN family, the members are defined by motifs containing two pairs of conserved histidines surrounded by asparagine residues (see Chevalier et al. (2001), Nucleic Acids Res. 29(18): 3757-3774). The four families of meganucleases are widely separated from one another with respect to conserved structural elements and, consequently, DNA recognition sequence specificity and catalytic activity.

Meganucleases are found commonly in microbial species and have the unique property of having very long recognition sequences (>14 bp) thus making them naturally very specific for cutting at a desired location. This can be exploited to make site-specific double-stranded breaks in genome editing. One of skill in the art can use these naturally occurring meganucleases, however the number of such naturally occurring meganucleases is limited. To overcome this challenge, mutagenesis and high throughput screening methods have been used to create meganuclease variants that recognize unique sequences. For example, various meganucleases have been fused to create hybrid enzymes that recognize a new sequence. Alternatively, DNA interacting amino acids of the meganuclease can be altered to design sequence specific meganucleases (see e.g., U.S. Pat. No. 8,021,867). Meganucleases can be designed using the methods described in e.g., Certo, M T et al. Nature Methods (2012) 9:073-975; U.S. Pat. Nos. 8,304,222; 8,021,867; 8,119,381; 8,124,369; 8,129,134; 8,133,697; 8,143,015; 8,143,016; 8,148,098; or 8,163,514, the contents of each are incorporated herein by reference in their entirety. Alternatively, meganucleases with site specific cutting characteristics can be obtained using commercially available technologies e.g., Precision BioSciences' Directed Nuclease Editor™ genome editing technology.

ZFNs and TALENs restriction endonuclease technology utilizes a non-specific DNA cutting enzyme which is linked to a specific DNA sequence recognizing peptide(s) such as zinc fingers and transcription activator-like effectors (TALEs). Typically, an endonuclease whose DNA recognition site and cleaving site are separate from each other is selected and the its cleaving portion is separated and then linked to a sequence recognizing peptide, thereby yielding an endonuclease with very high specificity for a desired sequence. An exemplary restriction enzyme with such properties is FokI. Additionally, FokI has the advantage of requiring dimerization to have nuclease activity and this means the specificity increases dramatically as each nuclease partner recognizes a unique DNA sequence. To enhance this effect, FokI nucleases have been engineered that can only function as heterodimers and have increased catalytic activity. The heterodimer functioning nucleases avoid the possibility of unwanted homodimer activity and thus increase specificity of the double-stranded break.

Although the nuclease portions of both ZFNs and TALENs have similar properties, the difference between these engineered nucleases is in their DNA recognition peptide. ZFNs rely on Cys2-His2 zinc fingers and TALENs on TALEs. Both of these DNA recognizing peptide domains have the characteristic that they are naturally found in combinations in their proteins. Cys2-His2 Zinc fingers typically happen in repeats that are 3 bp apart and are found in diverse combinations in a variety of nucleic acid interacting proteins such as transcription factors. TALEs on the other hand are found in repeats with a one-to-one recognition ratio between the amino acids and the recognized nucleotide pairs. Because both zinc fingers and TALEs happen in repeated patterns, different combinations can be tried to create a wide variety of sequence specificities. Approaches for making site-specific zinc finger endonucleases include, e.g., modular assembly (where Zinc fingers correlated with a triplet sequence are attached in a row to cover the required sequence), OPEN (low-stringency selection of peptide domains vs. triplet nucleotides followed by high-stringency selections of peptide combination vs. the final target in bacterial systems), and bacterial one-hybrid screening of zinc finger libraries, among others. ZFNs for use with the methods and compositions described herein can be obtained commercially from e.g., Sangamo Biosciences™ (Richmond, Calif.).

It is contemplated herein that the Cas9/CRISPR system of genome editing be employed with the methods and compositions described herein. Clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated (Cas) systems is useful for RNA-programmable genome editing (see e.g., Jinek, M. et al. Science (2012) 337(6096):816-821).

Alternatively, genome editing can be performed using recombinant adeno-associated virus (rAAV) based genome engineering, which is a genome-editing platform centered around the use of rAAV vectors that enables insertion, deletion or substitution of DNA sequences into the genomes of live mammalian cells. The rAAV genome is a single-stranded deoxyribonucleic acid (ssDNA) molecule, either positive- or negative-sensed, which is about 4.7 kilobase long. These single-stranded DNA viral vectors have high transduction rates and have a unique property of stimulating endogenous homologous recombination in the absence of causing double strand DNA breaks in the genome. One of skill in the art can design a rAAV vector to target a desired genomic locus and perform both gross and/or subtle endogenous gene alterations in a cell, such as a deletion. rAAV genome editing has the advantage in that it targets a single allele and does not result in any off-target genomic alterations. rAAV genome editing technology is commercially available, for example, the rAAV GENESIS™ system from Horizon™ (Cambridge, UK).

Pharmaceutically Acceptable Carriers

The methods of administering human hematopoietic progenitors to a subject as described herein involve the use of therapeutic compositions comprising hematopoietic progenitor cells. Therapeutic compositions contain a physiologically tolerable carrier together with the cell composition and optionally at least one additional bioactive agent as described herein, dissolved or dispersed therein as an active ingredient. In a preferred embodiment, the therapeutic composition is not substantially immunogenic when administered to a mammal or human patient for therapeutic purposes, unless so desired.

In general, the hematopoietic progenitor cells described herein are administered as a suspension with a pharmaceutically acceptable carrier. One of skill in the art will recognize that a pharmaceutically acceptable carrier to be used in a cell composition will not include buffers, compounds, cryopreservation agents, preservatives, or other agents in amounts that substantially interfere with the viability of the cells to be delivered to the subject. A formulation comprising cells can include e.g., osmotic buffers that permit cell membrane integrity to be maintained, and optionally, nutrients to maintain cell viability or enhance engraftment upon administration. Such formulations and suspensions are known to those of skill in the art and/or can be adapted for use with the hematopoietic progenitor cells as described herein using routine experimentation.

A cell composition can also be emulsified or presented as a liposome composition, provided that the emulsification procedure does not adversely affect cell viability. The cells and any other active ingredient can be mixed with excipients which are pharmaceutically acceptable and compatible with the active ingredient and in amounts suitable for use in the therapeutic methods described herein.

Additional agents included in a cell composition as described herein can include pharmaceutically acceptable salts of the components therein. Pharmaceutically acceptable salts include the acid addition salts (formed with the free amino groups of the polypeptide) that are formed with inorganic acids such as, for example, hydrochloric or phosphoric acids, or such organic acids as acetic, tartaric, mandelic and the like. Salts formed with the free carboxyl groups can also be derived from inorganic bases such as, for example, sodium, potassium, ammonium, calcium or ferric hydroxides, and such organic bases as isopropylamine, trimethylamine, 2-ethylamino ethanol, histidine, procaine and the like. Physiologically tolerable carriers are well known in the art. Exemplary liquid carriers are sterile aqueous solutions that contain no materials in addition to the active ingredients and water, or contain a buffer such as sodium phosphate at physiological pH value, physiological saline or both, such as phosphate-buffered saline. Still further, aqueous carriers can contain more than one buffer salt, as well as salts such as sodium and potassium chlorides, dextrose, polyethylene glycol and other solutes. Liquid compositions can also contain liquid phases in addition to and to the exclusion of water. Exemplary of such additional liquid phases are glycerin, vegetable oils such as cottonseed oil, and water-oil emulsions. The amount of an active compound used in the cell compositions as described herein that is effective in the treatment of a particular disorder or condition will depend on the nature of the disorder or condition, and can be determined by standard clinical techniques.

Administration & Efficacy

As used herein, the terms “administering,” “introducing” and “transplanting” are used interchangeably in the context of the placement of cells, e.g. hematopoietic progenitor cells, as described herein into a subject, by a method or route which results in at least partial localization of the introduced cells at a desired site, such as a site of injury or repair, such that a desired effect(s) is produced. The cells e.g. hematopoietic progenitor cells, or their differentiated progeny can be administered by any appropriate route which results in delivery to a desired location in the subject where at least a portion of the implanted cells or components of the cells remain viable. The period of viability of the cells after administration to a subject can be as short as a few hours, e.g., twenty-four hours, to a few days, to as long as several years, i.e., long-term engraftment. For example, in some embodiments of the aspects described herein, an effective amount of hematopoietic progenitor cells is administered via a systemic route of administration, such as an intraperitoneal or intravenous route.

When provided prophylactically, hematopoietic progenitor cells described herein can be administered to a subject in advance of any symptom of a hemoglobinopathy, e.g., prior to the switch from fetal γ-globin to predominantly β-globin. Accordingly, the prophylactic administration of a hematopoietic progenitor cell population serves to prevent a hemoglobinopathy, as disclosed herein.

When provided therapeutically, hematopoietic progenitor cells are provided at (or after) the onset of a symptom or indication of a hemoglobinopathy, e.g., upon the onset of sickle cell disease.

In some embodiments of the aspects described herein, the hematopoietic progenitor cell population being administered according to the methods described herein comprises allogeneic hematopoietic progenitor cells obtained from one or more donors. As used herein, “allogeneic” refers to a hematopoietic progenitor cell or biological samples comprising hematopoietic progenitor cells obtained from one or more different donors of the same species, where the genes at one or more loci are not identical. For example, a hematopoietic progenitor cell population being administered to a subject can be derived from umbilical cord blood obtained from one more unrelated donor subjects, or from one or more non-identical siblings. In some embodiments, syngeneic hematopoietic progenitor cell populations can be used, such as those obtained from genetically identical animals, or from identical twins. In other embodiments of this aspect, the hematopoietic progenitor cells are autologous cells; that is, the hematopoietic progenitor cells are obtained or isolated from a subject and administered to the same subject, i.e., the donor and recipient are the same.

For use in the various aspects described herein, an effective amount of hematopoietic progenitor cells, comprises at least 10² hematopoietic progenitor cells, at least 5×10² hematopoietic progenitor cells, at least 10³ hematopoietic progenitor cells, at least 5×10³ hematopoietic progenitor cells, at least 10⁴ hematopoietic progenitor cells, at least 5×10⁴ hematopoietic progenitor cells, at least 10⁵ hematopoietic progenitor cells, at least 2×10⁵ hematopoietic progenitor cells, at least 3×10⁵ hematopoietic progenitor cells, at least 4×10⁵ hematopoietic progenitor cells, at least 5×10⁵ hematopoietic progenitor cells, at least 6×10⁵ hematopoietic progenitor cells, at least 7×10⁵ hematopoietic progenitor cells, at least 8×10⁵ hematopoietic progenitor cells, at least 9×10⁵ hematopoietic progenitor cells, at least 1×10⁶ hematopoietic progenitor cells, at least 2×10⁶ hematopoietic progenitor cells, at least 3×10⁶ hematopoietic progenitor cells, at least 4×10⁶ hematopoietic progenitor cells, at least 5×10⁶ hematopoietic progenitor cells, at least 6×10⁶ hematopoietic progenitor cells, at least 7×10⁶ hematopoietic progenitor cells, at least 8×10⁶ hematopoietic progenitor cells, at least 9×10⁶ hematopoietic progenitor cells, or multiples thereof. The hematopoietic progenitor cells can be derived from one or more donors, or can be obtained from an autologous source. In some embodiments of the aspects described herein, the hematopoietic progenitor cells are expanded in culture prior to administration to a subject in need thereof.

In one embodiment, the term “effective amount” as used herein refers to the amount of a population of human hematopoietic progenitor cells or their progeny needed to alleviate at least one or more symptom of a hemoglobinopathy, and relates to a sufficient amount of a composition to provide the desired effect, e.g., treat a subject having a hemoglobinopathy. The term “therapeutically effective amount” therefore refers to an amount of hematopoietic progenitor cells or a composition comprising hematopoietic progenitor cells that is sufficient to promote a particular effect when administered to a typical subject, such as one who has or is at risk for a hemoglobinopathy. An effective amount as used herein would also include an amount sufficient to prevent or delay the development of a symptom of the disease, alter the course of a symptom disease (for example but not limited to, slow the progression of a symptom of the disease), or reverse a symptom of the disease. It is understood that for any given case, an appropriate “effective amount” can be determined by one of ordinary skill in the art using routine experimentation.

As used herein, “administered” refers to the delivery of a hematopoietic stem cell composition as described herein into a subject by a method or route which results in at least partial localization of the cell composition at a desired site. A cell composition can be administered by any appropriate route which results in effective treatment in the subject, i.e. administration results in delivery to a desired location in the subject where at least a portion of the composition delivered, i.e. at least 1×10⁴ cells are delivered to the desired site for a period of time. Modes of administration include injection, infusion, instillation, or ingestion. “Injection” includes, without limitation, intravenous, intramuscular, intra-arterial, intrathecal, intraventricular, intracapsular, intraorbital, intracardiac, intradermal, intraperitoneal, transtracheal, subcutaneous, subcuticular, intraarticular, sub capsular, subarachnoid, intraspinal, intracerebro spinal, and intrasternal injection and infusion. For the delivery of cells, administration by injection or infusion is generally preferred.

In one embodiment, the cells as described herein are administered systemically. The phrases “systemic administration,” “administered systemically”, “peripheral administration” and “administered peripherally” as used herein refer to the administration of a population of hematopoietic progenitor cells other than directly into a target site, tissue, or organ, such that it enters, instead, the subject's circulatory system and, thus, is subject to metabolism and other like processes.

The efficacy of a treatment comprising a composition as described herein for the treatment of a hemoglobinopathy can be determined by the skilled clinician. However, a treatment is considered “effective treatment,” as the term is used herein, if any one or all of the signs or symptoms of, as but one example, levels of fetal β-globin are altered in a beneficial manner, other clinically accepted symptoms or markers of disease are improved or ameliorated, e.g., by at least 10% following treatment with an inhibitor. Efficacy can also be measured by failure of an individual to worsen as assessed by hospitalization or need for medical interventions (e.g., progression of the disease is halted or at least slowed). Methods of measuring these indicators are known to those of skill in the art and/or described herein. Treatment includes any treatment of a disease in an individual or an animal (some non-limiting examples include a human, or a mammal) and includes: (1) inhibiting the disease, e.g., arresting, or slowing the progression of sepsis; or (2) relieving the disease, e.g., causing regression of symptoms; and (3) preventing or reducing the likelihood of the development of infection or sepsis.

The treatment according to the present invention ameliorates one or more symptoms associated with a β-globin disorder by increasing the amount of fetal hemoglobin in the individual. Symptoms typically associated with a hemoglobinopathy, include for example, anemia, tissue hypoxia, organ dysfunction, abnormal hematocrit values, ineffective erythropoiesis, abnormal reticulocyte (erythrocyte) count, abnormal iron load, the presence of ring sideroblasts, splenomegaly, hepatomegaly, impaired peripheral blood flow, dyspnea, increased hemolysis, jaundice, anemic pain crises, acute chest syndrome, splenic sequestration, priapism, stroke, hand-foot syndrome, and pain such as angina pectoris.

In one embodiment, the hematopoietic progenitor cell is contacted ex vivo or in vitro with a DNA targeting endonuclease, and the cell or its progeny is administered to the mammal (e.g., human). In a further embodiment, the hematopoietic progenitor cell is a cell of the erythroid lineage. In one embodiment, a composition comprising a hematopoietic progenitor cell that was previously contacted with a DNA-targeting endonuclease and a pharmaceutically acceptable carrier and is administered to a mammal.

In one embodiment, any method known in the art can be used to measure an increase in fetal hemoglobin expression, e.g., Western Blot analysis of fetal hemoglobin protein and quantifying mRNA of fetal γ-globin.

In one embodiment, the hematopoietic progenitor cell is contacted with a DNA-targeting endonuclease in vitro, or ex vivo. In one embodiment, the cell is of human origin (e.g., an autologous or heterologous cell). In one embodiment, the composition causes an increase in fetal hemoglobin expression.

The present invention can be defined in any of the following alphabetized paragraphs:

-   -   [A] A method for producing a progenitor cell having decreased         BCL11A mRNA or protein expression, the method comprising         contacting an isolated progenitor cell with an agent that binds         the genomic DNA of the cell on chromosome 2 location         60,716,189-60,728,612 (according to UCSC Genome Browser hg 19         human genome assembly), thereby reducing the mRNA or protein         expression of BCL11A.     -   [B] A method for producing an isolated genetic engineered human         cell having at least one genetic modification comprising         contacting an isolated cell with an effective amount of a         composition comprising at least a DNA-targeting endonuclease or         a vector carrying the coding sequence of a DNA-targeting         endonuclease whereby the DNA-targeting endonuclease cleaves the         genomic DNA of the cell on chromosome 2 location         60,716,189-60,728,612 causing at least one genetic modification         therein.     -   [C] The method of paragraph [A] or [B], wherein the isolated         progenitor cell or isolated cell is a hematopoietic progenitor         cell.     -   [D] The method of paragraph [C], wherein the hematopoietic         progenitor is a cell of the erythroid lineage.     -   [E] The method of paragraph [A] or [B], wherein the isolated         progenitor cell or isolated cell is an induced pluripotent stem         cell.     -   [F] The method of paragraph [C], wherein the hematopoietic         progenitor cell is contacted ex vivo or in vitro.     -   [G] The method of any one of paragraphs [A]-[F], wherein the at         least one genetic modification is a deletion.     -   [H] The method of paragraph [G], wherein the deletion removes         the entire region between chromosome 2 location         60,716,189-60,728,612 or removes a portion of the region         resulting in disruption of one or more DNAse 1-hypersensitive         sites (DHS).     -   [I] An isolated genetic engineered human cell having at least         one genetic modification on chromosome 2 location         60,716,189-60,728,612 according to paragraphs [B]-[H].     -   [J] A composition comprising isolated genetic engineered human         cells of paragraph [I].     -   [K] A method of increasing fetal hemoglobin levels in a cell,         the method comprising the steps of: contacting an isolated cell         with an effective amount of a composition comprising at least a         DNA-targeting endonuclease or a vector carrying the coding         sequence of a DNA-targeting endonuclease whereby the         DNA-targeting endonuclease cleaves the genomic DNA of the cell         on chromosome 2 location 60,716,189-60,728,612 causing at least         one genetic modification therein, whereby fetal hemoglobin         expression is increased in said cell, or its progeny, relative         to said cell prior to said contacting.     -   [L] The method of paragraph [K], wherein the isolated cell is a         hematopoietic progenitor cell.     -   [M] The method of paragraph [K] or [L], wherein the         hematopoietic progenitor cell is a cell of the erythroid         lineage.     -   [N] The method of paragraph [K], wherein the isolated cell is an         induced pluripotent stem cell.     -   [O] The method of paragraph [L] or [M], wherein the         hematopoietic progenitor cell is contacted ex vivo or in vitro.     -   [P] The method of any one of paragraphs [K]-[O], wherein the at         least one genetic modification is a deletion.     -   [Q] The method of paragraph [P], wherein the deletion removes         the entire region between chromosome 2 location         60,716,189-60,728,612 or removes a portion of the region         resulting in disruption of one or more DNAse 1-hypersensitive         sites (DHS).     -   [R] A method for increasing fetal hemoglobin levels in a mammal         in need thereof, the method comprising the steps of contacting         an isolated hematopoietic progenitor cell in said mammal with an         effective amount of a composition comprising at least a         DNA-targeting endonuclease or a vector carrying the coding         sequence of a DNA-targeting endonuclease whereby the         DNA-targeting endonuclease cleaves the genomic DNA of the cell         on chromosome 2 location 60,716,189-60,728,612 causing at least         one genetic modification therein, whereby fetal hemoglobin         expression is increased in said mammal, relative to expression         prior to the contacting.

This invention is further illustrated by the following example which should not be construed as limiting. The contents of all references cited throughout this application, as well as the figures and table are incorporated herein by reference.

EXAMPLE

The inventors have discovered and characterized regulatory elements of the BCL11A gene that are critical for its expression in erythroid lineage cells. Common genetic variants within these sequences are associated with fetal hemoglobin level and beta-globin disorder severity. These sequences comprise distal regulatory elements with an enhancer chromatin signature, possessing accessible chromatin, active histone marks, and occupancy by erythroid transcription factors. These elements interact with the BCL11A promoter and promote gene expression in erythroid cells but not other lineages that express BCL11A such as B-lymphocytes. These regulatory elements can be targeted for therapeutic purposes to achieve BCL11A inhibition and fetal hemoglobin reinduction. This can be achieved by mechanisms not limited to genome editing, nucleic acid or protein binding, and epigenetic modification. Advantages of this method include: disruption of a physiologic regulator of fetal hemoglobin level resulting in increased gamma-globin production and reduced beta-globin production; minimal effect on overall globin output or on red blood cell production or function; limitation of impact on cells outside of the erythroid lineage thus reducing potential toxicity.

Materials and Methods

Cell Culture

Human CD34+ cells from mobilized peripheral blood of healthy donors were obtained from Centers of Excellence in Molecular Hematology at Yale University, New Haven, Connecticut and Fred Hutchinson Cancer Research Center, Seattle, Wash. The cells were subject to ex vivo erythroid maturation with a two-phase serum-free liquid culture protocol as previously described (39). Peripheral blood mononuclear cells (PBMCs) were obtained from healthy donors from Boston Children's Hospital. Erythroid differentiation from PBMCs was performed as previously described (40). Mouse erythroleukemia (MEL) cells and 293T cells were cultured as previously described (39). Stably v-Abl transformed pre-B lymphocyte murine cells (derived as described (41)) were cultured in RPMI plus 2% penicillin-streptomycin, 15% FCS, 2% HEPES, 1% non-essential amino acids, 1% sodium pyruvate, 1% L-glutamine and 100 μM β-mercaptoethanol.

ChIP and DNase I Sensitivity

Chromatin immunoprecipitation and massively parallel sequencing were performed as described (39). The following antibodies were used: H3K27me3 (Millipore, 07-449), H3K4me3 (Millipore, 04-745), H3K4me1 (Abcam, ab8895), H3K27ac (Abcam, ab4729), RNA Polymerase II (PolII, Santa Cruz, sc-899), GATA1 (Abcam, ab11852) and TAL1 (Santa Cruz, sc-12984). DNase I cleavage density performed and analyzed as previously described (42). For ChIP-qPCR, relative enrichment was determined by comparing amplification of ChIP material to 1% input chromatin by the ΔCt method. Loci previously reported to be occupied and non-occupied by GATA1 and TAL1 were used as positive and negative controls respectively (39).

Chromosome Conformation Capture (3C)

3C assay was performed as previously described (39) except as below. Nuclei from formaldehyde cross-linked primary human erythroid precursors were digested with HindIII prior to ligation and reversal of cross-links. Quantitative real-time PCR was performed using iQ SYBR Green Supermix (Bio-Rad, 170-8880). A fragment containing the BCL11A promoter was used as the anchor region. To correct for amplification efficiency of different primers, a control template was prepared by digesting and ligating an equimolar mixture of two bacterial artificial chromosomes (BACs) comprising the complete human BCL11A locus (RP11-606L8 and RP11-139C22) and one the human β-globin cluster (CTD-3055E11). An interaction between fragments in HS1/HS2 and HS3 of the human β-globin locus control region (LCR) served as a positive control. Interaction frequency was expressed as amplification relative to the known LCR interaction, normalized to the BAC control template.

Fine-mapping BCL11A Locus

Markers (all coordinates hg19) were selected from within the three BCL11A intron-2 DHSs +62 (chr2:60,717,492-60,718,860), +58 (chr2:60,721,411-60,722,674) and +55 (chr2:60,724,802-60,726,084). 21 markers were identified from the 1000 Genomes Project database using the North European (CEU), Nigerian (YRI) and African-American (ASW) reference populations (Table S1). 38 additional variants were present in dbSNP135 (Table 2). The inventors sequenced by Sanger chemistry the three DHS intervals in the DNA of 52 and 36 sickle cell disease (SCD) patients from the CSSCD cohort with high (>8%) and low (<2%) HbF levels, respectively. From this sequencing effort, seven novel sequence variants were identified (Table 3). Because most markers cluster in small genomic intervals, it was not possible to design genotyping assays for some of them. Of 66 non-redundant variants identified in the three DHSs, genotyping assays for 40 markers were performed in 1,263 participants from the CSSCD, an African-American SCD cohort for which genomic DNA (gDNA) is available and HbF levels are known (21). Markers were genotyped using the Sequenom iPLEX platform. Individuals and DNA sequence variants with a genotyping success rate<90% were excluded. Overall genotype concordance estimated from triplicates was 100%. SNPs passing quality control (QC; n=38) are listed in Tables 2 and 3, and shown schematically in FIGS. 11A and 11B below the three DHSs. A substantial fraction of the genotyped SNPs are rare in the reference populations so not surprisingly monomorphic in the CSSCD (n=18). After QC, 1,178 individuals and 20 polymorphic SNPs remained for the analysis. HbF levels were modeled as previously described (9, 43). Association and conditional analyses of single variants (MAF>1%) were performed with PLINK (44) using linear regression under an additive genetic model. Analysis of common variants (MAF>1%) revealed that rs1427407 in DHS +62 had the strongest association to HbF level (P=7.23×10-50; FIGS. 11A and 3B). Conditional analysis demonstrated that after conditioning on rs1427407 and rs7606173, no more SNPs were significant (FIG. 3B). Adjusting for principal components (PCs) on 855 individuals for whom genome-wide genotyping data was available to account for admixture and other confounders yielded similar results.

For rare and low-frequency variants (MAF<5%), the inventors performed set-based analyses using each of the three DHSs +62, +58 and +55 as the testing unit. For these analyses, we used the sequence kernel association test (SKAT-O) program (45) with default parameters. The inventors selected the 5% threshold for MAF in order to maximize statistical power given our limited sample size, but note that markers with a MAF between 1% and 5% were also analyzed in the single variant analyses presented above. This variant overlap is accounted for using conditional analyses with the common variants independently associated with HbF levels. Two sets were found to be statistically significant, namely DHS +62 and DHS +55, but after conditioning on rs1427407 and rs7606173, results were no longer statistically significant, suggesting weak LD between the rare/low-frequency variants and the common SNPs (Table 5). The inventors did not find evidence that rare and low-frequency sequence variants within the BCL11A DHSs influence HbF levels in SCD subjects, despite Sanger re-sequencing these DHSs in 88 subjects with extreme HbF phenotype.

The rs1427407-rs7606173 haplotype frequencies in CSSCD are: T-G 24.5%, T-C 0.085%, G-C 42.3%, G-G 33.1%. The mean HbF level is 4.05% (SD 3.10) in 213 rs1427407-rs7606173 G-C individuals, 7.08% (SD 4.50) in 254 rs1427407-rs7606173 T-G/G-C heterozygotes and 11.21% (SD 4.37) in 60 rs1427407-rs7606173 T-G individuals (FIG. 3C). For comparisons of HbF levels between genotypes, the P-values were determined by one-tailed student t-tests.

Molecular Haplotyping

For two heterozygous SNPs on the same chromosome, there are two possible phases: A-B/a-b (model 1) and A-b/a-B (model 2). For SNPs within the 12-kb BCL11A intron-2 fragment +52.0-64.4 kb, phase was determined by cloning PCR products and determining co-distribution of SNP alleles. To determine phase of rs7569946 and rs1427407 alleles (separated by 30.1 kb on chromosome 2), emulsion fusion PCR was performed as previously described (24, 25) with minor modification. Fusion PCR brings two regions of interest, from separate parts of the same chromosome, together into a single product. By carrying out the reaction in emulsion with aqueous microdroplets surrounded by oil, the preponderance of amplicons are derived from a single template molecule. Genomic DNA from individuals known to be doubly heterozygous for rs7569946 and rs1427407 served as template in the following 100 μl reaction (with final concentrations listed): KOD Hot Start DNA Polymerase (14 U, Novagen, 71086), KOD buffer (1×), MgSO4 (1.5 mM), dNTPs (0.2 mM each), rs7569946-F and r51427407-R primers (1 μM each), rs7569946-R primer (30 nM), rs7569946-R-revcomp-r51427407-F bridging inner primer (30 nM), gDNA (200 ng). The 100 μl aqueous reaction was added dropwise with stirring to 200 μl oil phase to create an emulsion. Two 125 μl aliquots of emulsion were amplified under the following conditions: 95 degrees 2 minutes; 45 cycles of 95 degrees 20 seconds, 60 degrees 10 seconds, 70 degrees 30 seconds; 70 degrees 2 minutes. Hexane extracted fusion PCR product was subject to nested PCR in 25 μl as follows: KOD Hot Start DNA Polymerase (0.5 U), KOD buffer (1×), MgSO4 (1.5 mM), dNTPs (0.2 mM each), rs7569946-nested-F and rs1427407-nested-R primers (300 nM each), extracted fusion PCR product (75 nl); 95 degrees 2 minutes; 35 cycles of 95 degrees 20 seconds, 60 degrees 10 seconds, 70 degrees 30 seconds; 70 degrees 2 minutes. The nested product was confirmed by agarose gel electrophoresis to constitute a single band of expected size. The purified product was cloned with the Zero Blunt PCR Cloning kit (Life Technologies, K2700-20). The Sanger sequencing of fusion amplicons enumerated clones of 4 possible sequences: A-B, a-b, A-b and a-B. The likelihood of each phase was calculated based on a multinomial distribution assumption (Table 6). The likelihood ratio for the two configurations was calculated as a measure for the statistical significance of the data fitting haplotype model 1 (as compared to model 2). A ratio approaching infinity suggests model 1, a ratio of 1 suggests equipoise and a ratio approaching zero suggests model 2.

Pyrosequencing

Healthy CD34+ cell donors were screened to identify five donors heterozygous for rs1427407. These CD34+ cells were subject to ex vivo erythroid differentiation. Chromatin was isolated and ChIP performed with GATA1 and TAL1 antibodies. Input chromatin as compared to GATA1 or TAL1 precipitated material was subject to pyrosequencing to determine allelic balance of rs1427407. Healthy CD34+ donors were screened to identify three donors heterozygous for the rs1427407-rs7606173 G-C/T-G haplotype. These CD34+ cells were subject to ex vivo erythroid differentiation. Complementary DNA (cDNA) and gDNA were subject to pyrosequencing to determine allelic balance of rs7569946.

PCR conditions as follows: 2X HotStarTaq master mix (QIAGEN, 203443), MgCl₂ (final concentration 3 mM), template DNA (0.1-1 ng) and SNP-specific forward and reverse-biotinylated primers (200 nM each). PCR cycling conditions were: 94° C. 15 min; 45 cycles of 94° C. 30 s; 60° C. 30 s; 72° C. 30 s; 72° C. 5 min. One primer of each pair was biotinylated. The PCR product strand containing the biotinylated primer was bound to streptavidin beads and combined with a specific sequencing primer. The primed single stranded DNA was sequenced and genotype analyzed using the Pyrosequencing PSQ96 HS System (QIAGEN Pyrosequencing) following the manufacturer's instructions.

Transgenic Mice

The enhancer reporter construct pWHERE-Dest was obtained from Dr. William Pu. Modified from pWHERE (Invitrogen, pwhere) as previously described (46), the construct has murine H19 insulators flanking a CpG-free lacZ variant driven by a minimal Hsp68 minimal promoter with a Gateway destination cassette at the upstream MCS Enhancer fragments were amplified from mouse gDNA, recombined into pDONR221 vector (Invitrogen, 12536-017) by BP clonase (Invitrogen, 11789020) and recombined into pWHERE-Dest vector with LR clonase (Invitrogen, 11791020). Plasmids were digested with Pad to remove vector backbone. The lacZ enhancer reporter fragments were purified by gel electroelution and then concentrated using Wizard DNA Clean-Up System (Promega, A7280). Transgenic mice were generated by pronuclear injection to FVB fertilized eggs. Approximately 10 ng/μl of DNA solution was used for series of injections. CD-1 females were used as recipients for injected embryos. 10.5 to 14.5 dpc embryos were dissected from surrogate mothers with whole-mount and tissue X-gal staining performed as previously described (47). X-gal stained cytospins were counterstained with Nuclear Fast Red (Vector Laboratories, H-3403). Tails used for PCR genotyping. Animal procedures were approved by the Children's Hospital Instititutional Animal Care and Use Committee.

Human Erythroid Precursor Enhancer Assay

Genomic DNA fragments containing putative enhancer elements were cloned into pLVX-Puro (Clontech, 632164) upstream of a minimal TK promoter and GFP reporter gene as described (39). 293T cells were transfected with FuGene 6 reagent (Promega, E2691) according to manufacturer's protocol. The media was changed after 24 hours to SFEM medium supplied with 2% penicillin-streptomycin, and after 36 hours, supernatant was collected and filtered. CD34+ cell-derived erythroid cultures were transduced with lentivirus on expansion days 4 and 5 by spin-infection as previously described (39). Cells were resuspended in erythroid differentiation media 24 hours after the second infection. Selection with puromycin 1 μg/ml commenced 48 hours after infection. Transduced cells were analyzed after five days in differentiation media by flow cytometry for GFP mean fluorescence intensity.

Flow Cytometry

Live cells were gated by exclusion of 7-aminoactinomycin D (7-AAD, BD Pharmingen, 559925). Bone marrow (for erythroblast) and spleen (for lymphocyte) suspensions were isolated from young adult transgenic mice. Following hypotonic lysis of mature red blood cells, live cells (7-AAD-) sorted based on staining with CD71-biotin (BD, 557416), streptavidin-APC (BD, 554067), Ter-119-PE (BD, 553673), CD19-APC (BD, 550992) or CD3-PE (BD, 100308). CD71+Ter119+, CD19+ and CD3+ sorted populations used for cytospin and RNA isolation.

TALEN-Mediated Chromosomal Deletion

Transcription activator-like effector nucleases (TALENs) were designed to generate cleavages at mouse Bcl11a intron-2 at sites +50.4 kb (termed 5′ site) and +60.4 kb (3′ site) relative to the TSS. The TALENs recognize the following sequences: CTTAAGGCAAGAATCACT (SEQ ID NO: 2) (5′ left), CCATGCCTTTCCCCCCCT (SEQ ID NO: 3) (5′ right), GAGTTAAAATCAGAAATCT (SEQ ID NO: 4) (3′ left), CTGACTAATTGATCAT (SEQ ID NO: 5) (3′ right). TALENs were synthesized with Golden Gate cloning (48) using the NN RVD to recognize G. The synthesized DNA binding domains were cloned into pcDNA3.1 (Invitrogen, V790-20) with the FokI nuclease domain, A152 N-terminal domain and +63 C-terminal domain previously described (49). 2.5 μg of each of the four TALEN plasmids with 0.5 μg pmaxGFP (Lonza) were delivered to 2×10⁶ MEL or pre-B cells by electroporation per manufacturer's protocol (Lonza, VCA-1005). GFP-positive cells were sorted by flow cytometry after 48 hours. Cells seeded by limiting dilution in 96-well plates to isolate individual clones. Clones screened by PCR of gDNA to detect the amplification of a short product from upstream of the 5′ site and downstream of the 3′ site indicating deletion of the intervening segment. Monoallelic deleted clones were subject to a second round of TALEN-mediated deletion to obtain biallelic deleted clones. Clones with biallelic deletion were identified by detecting absence of amplification from within the deleted fragment. Deletion frequency was approximately one in 50 alleles. Deletion was validated with Southern blotting. Genomic DNA was digested with BmtI; a 561-bp probe (amplified from gDNA upstream of the 5′ site) hybridizes to a 3.6 kb fragment from the wild-type allele and a 8.9 kb fragment from the Δ50.4-60.4 deleted allele.

RT-qPCR and Immunoblotting

RNA isolation with RNeasy columns (Qiagen, 74106), reverse transcription with iScript cDNA synthesis kit (Bio-Rad, 170-8890), qPCR with iQ SYBR Green Supermix (Bio-Rad, 170-8880) and immunoblotting performed as described (39). For the mouse β-globin cluster genes, a common primer pair recognizes the adult β-globins β2 and β1 while independent primers recognize the embryonic β-globins εy and βH1. The following antibodies were used for immunoblotting: BCL11A (Abcam, ab19487), GAPDH (Santa Cruz, sc-25778).

Results

Genome-wide association studies (GWAS) have ascertained numerous common genetic variants associated with traits, frequently localized to regulatory DNA. The hypothesis that regulatory variation may account for substantial heritability has undergone scarce experimental evaluation. Here the inventors show that a common genetic variation at BCL11A associated with fetal hemoglobin (HbF) level indicates noncoding sequences decorated by an erythroid enhancer chromatin signature. Fine mapping within this putative regulatory DNA reveals a motif-disrupting common variant associated with reduced transcription factor binding, diminished BCL11A expression, and elevated HbF. The surrounding sequences function in vivo as a developmental stage-specific lineage-restricted enhancer. By genome engineering, it was shown that this enhancer is required for erythroid BCL11A expression yet dispensable outside the erythroid lineage. These results illustrate how GWAS can highlight functional variants of modest impact within causal elements essential for appropriate gene expression. The GWAS-marked BCL11A enhancer represents a favorable therapeutic target for the β-globin disorders.

GWAS have been tremendously successful in identifying many thousands of common single nucleotide polymorphisms (SNPs) associated with human traits and diseases. However, advancing from genetic association to causal biologic process has often been difficult. Challenges include the large number of correlated variants that may be associated with individual traits (owing to linkage disequilibrium (LD)), the modest effect size of many variant-trait associations, and the location of many associated variants in the noncoding genome. Recent genome-scale chromatin mapping studies have highlighted the enrichment of GWAS variants in regulatory DNA elements, suggesting many causal variants may affect gene regulation. Nonetheless, few examples confirming the significance of causal variants or elements have been experimentally demonstrated.

The GWAS of HbF level have been particularly striking. Genetic variation at just three loci (HBB,HBS1L-MYB, and BCL11A) accounts for up to 50% of the heritable variation in HbF level. The same variants are also associated with the clinical severity of the major β-globinopathies sickle cell disease and β-thalassemia, perhaps not surprisingly since HbF is a major modifier of these disorders. Work from the inventor's laboratory and others have validated that BCL11A is a direct regulator of HbF levels. BCL11A is a transcriptional repressor that resides within multiprotein complexes occupying the β-globin gene cluster. While constitutive BCL11A deficiency results in embryonic lethality and impaired lymphocyte development, erythroid-specific deficiency of BCL11A counteracts developmental silencing of embryonic and fetal globin genes and is sufficient to rescue the hematologic and pathologic features of sickle cell disease in mouse models. Therefore, BCL11A has emerged as a novel therapeutic target for the β-globin disorders. Understanding the consequences of impaired BCL11A is imperative. Human coding variants of BCL11A have not been described despite large-scale resequencing efforts. The BCL11A variants associated with HbF levels reside in noncoding regions of BCL11A. To further understand how common genetic variation impacts BCL11A, HbF level, and β-globin disorder severity, the role of HbF-associated variants was investigated in detail.

Trait-Associated Variants Near Erythroid Enhancers

Numerous GWAS as well as follow-up fine-mapping studies have been performed of erythroid traits (including phenotypes such as erythrocyte number and volume, hemoglobin concentration, and HbF level), identifying 636 trait-associated SNPs at genome-wide significance (p<5e⁻⁸). These SNPs are enriched in promoters and coding regions as compared to random SNPs (FIG. 1). Still the majority of the SNPs reside elsewhere in the genome. A global chromatin profiling of primary human erythroid precursors was performed, which identified an extensive set of distal erythroid enhancers defined by characteristic histone modifications and DNase I hypersensitivity. A strong colocalization of erythroid GWAS SNPs with enhancers was observed as compared to non-erythroid trait-associated SNPs, SNPs found on a common genotyping array, or randomly permuted SNPs. 13.5% of the erythroid trait-associated SNPs fell directly into erythroid enhancers, an 11.4-fold enrichment over random permuted enhancers (P<1×10⁻⁴), as compared to 1.4% of non-erythroid trait-associated SNPs, representing a 1.4-fold enrichment (P=0.0013). Many of the erythroid trait-associated SNPs were found in close proximity to erythroid enhancers (FIG. 1B). The median distance to erythroid enhancer was 16.0 kilobases (kb) for erythroid trait-associated SNPs, as compared to 238.0, 392.6, and 482.4 kb respectively for non-erythroid trait-associated, genotyping array, and randomly permuted SNPs. These results indicate that a substantial fraction of common variants associated with erythroid traits reside at or near erythroid enhancers, and are consistent with the hypothesis that causal variants often influence context-dependent gene regulation.

HbF GWAS Mark an Erythroid Enhancer Signature

Six GWAS have been conducted of HbF level (or the highly correlated trait F-cell number), including populations of European, African, and Asian descent. Each has identified trait-associated variants within BCL11A. Variation at BCL11A is estimated to explain ˜15% of the trait variance. Four different SNPs have been identified as most highly associated with the trait (rs1427407, rs11886868, rs4671393, and rs766432; these so-called “sentinel” SNPs cluster within 3 kb of each other in BCL11A intron-2 (FIG. 2A). Haplotypes including the sentinel SNPs appear to better explain the HbF association than any individual SNP. Fifty SNPs at the BCL11A locus and twenty-seven SNPs within intron-2 have been associated with HbF level with at least genome-wide significance (P<5×10⁻⁸).

The distribution of the HbF-associated SNPs at BCL11A were compared with DNase I sensitivity, an indicator of chromatin state suggestive of regulatory potential. In human erythroid precursors, three peaks of DNase I hypersensitivity were observed in intron-2, adjacent to and overlying the HbF-associated variants (FIG. 2A), termed DNase I hypersensitive sites (DHSs) +62, +58, and +55 based on distance in kb from the TSS of BCL11A. Brain and B-lymphocytes, two tissues that express high levels of BCL11A, and T-lymphocytes, which do not express appreciable BCL11A, show unique patterns of DNase I sensitivity at the BCL11A locus, with a paucity of DNase I hypersensitivity overlying the trait-associated SNPs (FIG. 2A).

The chromatin signature around the BCL11A locus was further analyzed by chromatin immunoprecipitation with massively parallel sequencing (ChIP-seq). ChIP-seq from primary human erythroid precursors revealed histone modifications with an enhancer signature overlying the trait-associated SNPs at BCL11A intron-2, including the presence of H3K4me1 and H3K27ac and absence of H3K4me3 and H3K27me3 marks (FIG. 2A). The master erythroid transcription factors GATA1 and TAL1 occupy this enhancer region (FIG. 2A). ChIP-qPCR experiments demonstrated three discrete peaks of GATA1 and TAL1 binding within BCL11A intron-2, each falling within an erythroid DHS (FIG. 2B).

One common feature of distal regulatory elements is long-range interaction with the promoters whose expression they regulate. The interactions between the BCL11A promoter and fragments across 250 kb of the BCL11A locus were evaluated, including sequences upstream, downstream, and intragenic. The greatest promoter interaction was observed within the region of intron-2 containing the erythroid DHS and trait-associated SNPs (FIG. 2C). These results indicate that these sequences have regulatory potential.

Regulatory Variants

It was hypothesized that the causal trait-associated SNPs could function by modulating critical cis-regulatory elements. Therefore, extensive genotyping of SNPs was performed within the three erythroid DHSs +62, +58, and +55 in 1263 DNA samples from the Cooperative Study of Sickle Cell Disease (CSSCD), an African-American sickle cell disease cohort for which genomic DNA is available and HbF levels are known. 66 DNA sequence variants located in the three DHSs from dbSNP were identified from reference populations CEU, YRI, and ASW within the 1000 Genomes Project, and by Sanger sequencing 88 individuals from the CSSCD with extreme HbF phenotype. 26 markers failed genotyping assay design and 18 were monomorphic (Tables 1 and 2). After quality control, 1178 individuals and 20 polymorphic SNPs remained for association testing. Analysis of common variants (minor allele frequency (MAF)>1%) revealed that rs1427407 in DHS +62 had the strongest association to HbF level (P=7.23×10⁻⁵⁰, Table 1).

Previously, the inventors had used the CSSCD to fine-map the association signal with HbF at the BCL11A locus and reported a strong association with rs4671393; in that study, rs1427407 was imputed. Two additional SNPs, rs766432 and rs11886868 have also been identified in prior studies as sentinel SNPs most highly associated with HbF level (or F-cell number). In a subset of individuals (N=728) for which genotypes at all four sentinel SNPs were known, when conditioned on genotypes at rs1427407, the association result was not significant at rs4671393, rs766432, or rs11886868; conversely, the association remained highly significant for rs1427407 when conditioning on rs4671393, rs766432, or rs11886868 (Table 3). Therefore, rs1427407 is the SNP most associated with HbF within the erythroid DHS and better accounts for the trait association than other previously described sentinel SNPs.

When conditioned on rs1427407, other associations to HbF level were found within the three DHSs that were not completely lost (Table 1). The most significant association remaining was for rs7606173 in DHS +55 (P=5.11×10⁻¹⁰); rs7599488 in DHS +58, which were previously reported, was only slightly less significant (P=1.71×10⁻⁹) in this conditional analysis. After conditioning on rs1427407 and rs7606173, no more SNPs were significant (Table 1). Adjusting for principal components (PCs) on 855 individuals for whom genome-wide genotyping data was available to account for admixture and other confounders yielded similar results (data not shown). The rs1427407-rs7606173 T-G haplotype was defined as that most highly associated with HbF level.

Rare and low-frequency variants (MAF<5%) were also analyzed for their association with HbF levels using each of the three DHSs +62, +58, and +55 as a testing set. Two sets were found to be significant, namely DHS +62 and DHS +55, but after conditioning on rs1427407 and rs7606173, results were no longer significant, indicating weak LD between the rare/low-frequency variants and the common SNPs (Table 4). Therefore, no evidence that rare and low-frequency sequence variants within the BCL11A DHSs influence HbF levels in SCD patients was found, despite Sanger resequencing 88 individuals from CSSCD with extreme HbF phenotype.

The SNP rs1427407 falls within a peak of GATA1 and TAL1 binding as determined by ChIP-seq and ChIP-qPCR (FIGS. 2A and 2B). The minor T-allele disrupts the G-nucleotide of a sequence element highly resembling a half-E-box/GATA composite motif [CTG(n₉)GATA (SEQ ID NO: 6)]. This motif has been found to be highly enriched by GATA1 and TAL1 complexes in erythroid cells by ChIP-seq experiments. Primary erythroid samples were identified from individuals heterozygous for the major G-allele and minor T-allele at rs1427407 and subjected these samples to ChIP followed by pyrosequencing. The inventors identified an even balance of alleles in the input DNA. However more frequent binding to the G-allele was observed compared to the T-allele of approximately 60:40 in both the GATA1 and TAL1 immunoprecipitated chromatin samples (FIG. 3A).

It was previously reported that the high-HbF associated A-allele of rs4671393 was associated with BCL11A expression in human lymphoblastoid cell lines. The inventors were unable to reproduce a significant association between BCL11A genotype and expression level analyzing a larger set of lymphoblastoid cell lines (data not shown). It was speculated that the high-HbF-associated rs1427407-rs7606173 haplotype influences BCL11A expression in an erythroid-specific context. The common synonymous SNP rs7569946 lies within exon-4 of BCL11A and may serve as a marker of allelic expression. Three primary human erythroid samples were identified that were doubly heterozygous for the rs1427407-rs7606173 haplotype and rs7569946. The samples were subjected to molecular haplotyping by emulsion fusion PCR. The haplotyping demonstrated that for each sample the major rs7569946 G-allele was in phase with the low-HbF-associated rs1427407-rs7606173 G-C haplotype. Genomic DNA and cDNA were assayed by pyrosequencing of rs7569946 to determine allelic balance. Whereas the alleles were balanced in the genomic DNA, significant imbalance in the cDNA favoring increased expression of the low-HbF linked G-allele of rs7569946 was observed (FIG. 3B). These results indicate that the high-HbF rs1427407 T-allele, which disrupts the half-E-box/GATA motif, is associated with reduced binding of GATA1 and TAL1 and reduced expression of BCL11A in erythroid precursors. The mean HbF level in 60 high-HbF rs1427407-rs7606173 T-G haplotype homozygous individuals was 11.21% as compared to 4.05% in 213 low-HbF rs1427407-rs7606173 G-C haplotype homozygous individuals (P=2.5×10⁻¹⁹) (FIG. 3C). In sum, the following evidence indicates that rs1427407 is a causal SNP for HbF level: it has the highest association to the phenotype of any known variant, it accounts for the associations observed with previously described sentinel SNPs, it impacts a motif required for GATA1 and TAL1 binding, and it is associated with GATA1 and TAL1 binding as well as with BCL11A expression. However, variation at this position in the setting of common haplotypes is associated with only modest perturbation of BCL11A expression.

Enhancer Sufficiency for Erythroid Expression

To understand the context within which these apparent regulatory trait-associated SNPs play their role, the function of the harboring cis-regulatory elements was explored. The inventors cloned ˜12-kb (+52.0-64.4 kb from TSS) which contained the three erythroid DHSs, and assayed enhancer potential in a transgenic reporter assay. In this assay putative enhancer sequences are positioned upstream of a minimal promoter (Hsp68) and reporter gene (lacZ) bounded by insulator sequences. Constructs were introduced to murine zygotes with reporter gene expression monitored throughout development. Endogenous mouse BCL11A showed abundant expression throughout the developing central nervous system with much lower expression observed in the fetal liver. In contrast, reporter gene expression in the transgenic embryos was observed to be largely confined to the fetal liver, the site of definitive erythropoiesis, with lesser expression noted in the central nervous system (FIG. 4A).

A characteristic feature of globin genes is their developmental regulation. During human development, yolk sac-derived ε-globin is superseded in the first trimester by fetal liver-derived γ-globin. Around birth, γ-globin is gradually silenced and β-globin becomes activated. There is only a single switch in gene expression during mouse ontogeny. During this transition, which occurs at mid-gestation, the circulating yolk sac-derived primitive erythrocytes express embryonic-stage globins εy and βH1 whereas the fetal liver definitive erythroblasts express adult-stage globins β1 and β2. Concordant with this developmental switch, BCL11A expression is expressed in the definitive but not primitive stage erythroid lineage. Stable transgenic lines were derived from the BCL11A +52.0-64.4 reporter mice. In these mice at E12.5 circulating erythrocytes do not stain for X-gal whereas liver erythroblasts robustly stain positive (FIG. 4B). At E10.5 lacZ expression is only observed in the fetal liver primordium and not in the circulating blood within the embryo, placenta, or yolk sac (FIG. 6A). These results indicate that the GWAS-marked BCL11A intron-2 regulatory sequences are sufficient to specify developmentally appropriate gene expression.

Within the hematopoietic compartment, BCL11A expression is found in erythroid precursors and B-lymphocytes. Erythroid precursors and B-lymphocytes were isolated from transgenic young adult animals and expression of the lacZ reporter gene was evaluated. Endogenous BCL11A was expressed at 10.4-fold higher levels in splenic B-lymphocytes as compared to bone marrow erythroid precursors. However, lacZ expression was restricted to erythroid precursors and was not observed in B-lymphocytes (FIG. 4C). These results indicate erythroid-specificity of these regulatory sequences.

A series of deletion mutants was generated to refine the minimal elements required for erythroid enhancer activity. Sequences containing the central +58 DHS were sufficient for erythroid enhancer activity. Those sequences containing only the flanking +62 or +55 elements were not able to direct erythroid gene expression (FIG. 6B). These DHSs were also tested for their ability to enhance gene expression in primary human erythroid precursors. The inventors used lentiviral delivery of a GFP reporter system with a minimal TK promoter as previously described. Similarly, only the +58 but not the +55 or +62 DHSs were able to enhance gene expression in this reporter assay (FIG. 7).

Enhancer Requirement for Erythroid Expression

Next the inventors chose to determine the requirement of these regulatory sequences for appropriate expression of BCL11A and globin genes. Inspection of the Bcl11a locus in previously published global chromatin profiling of mouse erythroid cells revealed that this region of intron-2 possesses an orthologous enhancer signature with presence of H3K4me1 and H3K27ac, absence of H3K4me3 and H3K27me3, and occupancy by GATA1 and TAL1 (FIG. 8). Moreover, erythroid-specific DNase I hypersensitivity was observed at these sequences. At each of the human erythroid DHSs +62, +58, and +55, evidence of evolutionary sequence conservation was observed, particularly within +62 and +55. To determine the requirement of these orthologous regulatory sequences for BCL11A expression, the mouse erythroleukemia cell line (MEL) was used. These cells depend on BCL11A expression for appropriate adult-stage pattern globin gene expression. Sequence-specific nucleases can result in the production of small chromosomal deletions. TALENs were engineered to introduce double-strand breaks to flank the orthologous 10-kb Bcl11a intron-2 sequences carrying the erythroid enhancer chromatin signature. Clones were screened for NHEJ-mediated repair and three unique clones were isolated that had undergone biallelic excision. PCR and Southern blotting verified excision of the intronic segment within clones (FIG. 9). Sanger-sequenced breakpoints were characteristic of TALEN-mediated cleavage with subsequent NHEJ repair (FIG. 10).

Expression of BCL11A was analyzed in the MEL cells with biallelic 10-kb intronic deletion. A dramatic reduction of BCL11A expression to ˜3% of baseline levels was observed (FIG. 5A). Similar reductions were noted with primer pairs detecting exon junctions upstream, spanning, or downstream of the deletion. By Western blotting, BCL11A expression was not detectable in the 10-kb enhancer deleted clones (FIG. 5B). MEL cells typically express high levels of the adult globin genes β1 and β2 and low levels of the embryonic globin genes εy and βH1. In the absence of the 10-kb enhancer for BCL11A, expression of adult globin genes was decreased by ˜2-5-fold, whereas embryonic globin genes were considerably derepressed. The ratio of embryonic εy to adult β1/2 was increased by a mean of 364-fold in three clones lacking the orthologous BCL11A erythroid enhancer (FIG. 5C).

To determine if the +50.4-60.4 kb intronic sequences were universally required for BCL11A expression, their loss was evalutated in a non-erythroid context. The same strategy of introduction of two pairs of TALENs to obtain clones with the NHEJ-mediated Δ50.4-60.4 deletion was employed in a pro-B lymphocyte cell line. Two unique Δ50.4-60.4 clones were isolated, and verified by PCR, Southern blotting, and Sanger sequencing (FIGS. 9 and 10). In contrast to the erythroid cells, BCL11A expression was retained in the Δ50.4-60.4kb enhancer deleted pro-B cell clones at both the RNA and protein levels (FIGS. 5A and 5B). These results indicate the orthologous erythroid enhancer sequences are not required for integrity of transcription from the Bcl11a locus but only essential for erythroid gene expression.

An enhancer chromatin signature was found at intron-2 of BCL11A, directly overlying the HbF-associated SNPs. This region had numerous biochemical features of an enhancer, including occupancy by the histone marks H3K4me1 and H3K27ac in the absence of H3K4me3 and H3K27me3, binding of the erythroid TFs GATA1 and TAL1, erythroid-specific DNase-I hypersensitive sites, and long-range promoter interaction by 3C. Moreover, the inventors were able to fine-map this locus, using the DHSs as a guide, to identify the SNP rs1424707 as being most highly associated with the trait, and entirely accounting for the trait association of the previously described and highly linked sentinel SNPs. In addition, it is shown herein that rs1427407 disrupts a half-E-box/GATA motif occupied by the transcription factors GATA1 and TAL1 in erythroid precursors. However, even after conditioning on rs1427407 an association remains with several other SNPs in adjacent DHSs indicating a haplotype effect. It was found that haplotypes which possess a combination of SNP genotypes in adjacent elements that each modulate regulatory function cooperate to give the ultimate phenotype of BCL11A expression. Using heterozygous donors, a modest impact of the high-HbF associated haplotype was demonstrated on both TF binding and BCL11A expression.

These studies help to estimate the change in BCL11A expression required to result in a clinically meaningful increase in HbF level in patients with β-globin disorders. The difference in BCL11A expression between the high-HbF rs1427407-rs7606173 T-G and low-HbF G-C haplotypes was 1.7-fold and the HbF levels of T-G and G-C homozygotes were 11.2% and 4.1% (FIGS. 3B and 3C). HbF levels of >20% have been predicted to prevent the adverse consequences of SCD. A reduction in BCL11A expression of several-fold would likely approach this HbF goal.

This study identifies regulatory variation at BCL11A that impacts an erythroid enhancer. Many trait-associated SNPs are noncoding and have relatively small effect size. Due to these features, these SNPs are sometimes considered to be of negligible clinical importance. This study illustrates that a small effect size engendered by an individual noncoding variant does not preclude a large effect size of the underlying regulatory element. For example, despite a relatively modest impact of functional SNPs on expression of the underlying gene target BCL11A, the causal regulatory elements are essential for expression of BCL11A and globin genes in adult-stage erythroid precursors. The same regulatory element is dispensable for BCL11A expression in a non-erythroid lineage. A goal of studying protective alleles is to understand their underlying molecular mechanisms in an effort to reproduce this biological effect in at-risk individuals. Thus, many trait-associated polymorphisms will reside context-specific critical regulatory elements whose function may further illuminate the underlying biology of the trait beyond merely identifying the regulated gene. For example loss of BCL11A while resulting in impaired hemoglobin switching also results in impaired neurogenesis and lymphopoeisis and results in embryonic lethality. Ultimately a better understanding of the causal regulatory elements and associated regulatory networks underlying traits could identify novel therapeutic targets. The erythroid enhancer of BCL11A could itself constitute a favorable target for therapeutic genome editing in that ablation could impede BCL11A expression in erythroid precursors with resultant HbF derepression while preserving BCL11A expression in non-erythroid lineages.

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TABLE 1 Association analysis of common SNPs in BCL11A DHSs +62, +58, or +55 Conditional on Conditional on rs1427407 and rs1427407 rs7606173 DHS Marker MAF β P β P β P +62 rs111575474 0.0153 −0.2624 0.09762 −0.0851 0.5584  0.0486 0.7368 +62 rs112105713 0.0115 −0.3285 0.07755 −0.2137 0.2097  −0.0859 0.6107 +62 rs74958177 0.0646 −0.3614 2.79 × 10⁻⁶  −0.1838 0.01041 −0.0832 0.2518 +62 rs1427407 0.2460 0.6634 7.23 × 10⁻⁵⁰ — — — — +62 rs7599488 0.3148 −0.0047 0.9116   0.2622 2.43 × 10⁻¹⁰ 0.0915 0.3547 +62 rs1896293 0.1089 −0.2623 2.52 × 10⁻⁵  −0.1248 0.03098 0.0241 0.6952 +58 rs6738440 0.2734 −0.3820 1.25 × 10⁻¹⁸ −0.1935 5.64 × 10⁻⁶  −0.0223 0.6887 +55 rs147910897 0.0132 −0.3656 0.03294 −0.2586 0.09945 −0.1575 0.3101 +55 rs148529953 0.0140 −0.3521 0.04034 −0.1423 0.3668  −0.0098 0.9501 +55 rs7606173 0.4238 −0.4691 2.86 × 10⁻³⁴ −0.2632 9.66 × 10⁻¹¹ — — Association analysis of common (MAF >1%) SNPs in BCL11A DHSs +62, +58, or +55 from 1178 individuals from CSSCD available for analysis. DHS, DNase I hypersensitive site. MAF, minor allele frequency.

TABLE 2 SNPs within BCL11A DHSs +62, +58, or +55 Major Minor Marker CHR POS Allele Allele DHS Genotyped MAF rs149113684 2 60,717,544 C A +62 Monomorphic 0.0000 rs111575474 2 60,717,559 C T +62 YES 0.0157 rs148272134 2 60,717,643 C A +62 Failed Assay Design — rs182773253 2 60,717,676 A G +62 Monomorphic 0.0000 rs188706265 2 60,717,769 C T +62 Monomorphic 0.0000 rs74958177 2 60,717,776 A G +62 YES 0.0645 rs1427407 2 60,718,043 G T +62 YES 0.2460 rs35262352 2 60,718,076 A — +62 Failed Assay Design — rs79781583 2 60,718,077 A T +62 Failed Assay Design — rs201428515 2 60,718,088 G A +62 Monomorphic 0.0000 rs112105713 2 60,718,278 G A +62 YES 0.1145 rs7599488 2 60,718,347 C T +62 YES 0.3149 rs113636744 2 60,718,540 C T +62 YES 0.0042 rs35259900 2 60,718,555 C T +62 Failed Assay Design — rs111911554 2 60,718,569 A G +62 Failed Assay Design — rs137943695 2 60,718,574 G A +62 Monomorphic 0.0000 rs45579333 2 60,718,599 G A +62 Monomorphic 0.0000 rs77876582 2 60,718,639 C T +62 Failed Assay Design — rs112634025 2 60,718,708 G A +62 Failed Assay Design — rs45439602 2 60,718,721 G A +62 Failed Assay Design — rs112387548 2 60,718,762 C T +62 Failed Assay Design — rs191369155 2 60,718,781 G A +62 Failed Assay Design — rs6723022 2 60,718,807 A C +62 Monomorphic 0.0000 rs11422901 2 60,718,819 G A +62 Failed Assay Design — rs200632291 2 60,718,824 A G +62 Failed Assay Design — rs11387709 2 60,718,826 A — +62 Failed Assay Design — rs1896293 2 60,718,848 G T +62 YES 0.1088 rs71526487 2 60,721,587 T C +58 Failed Assay Design — rs185151573 2 60,721,639 G C +58 Monomorphic 0.0000 rs6721788 2 60,721,846 T C +58 YES 0.0025 rs76033449 2 60,721,900 G A +58 YES 0.0004 rs6706648 2 60,722,040 T C +58 Failed Genotyping — rs62142615 2 60,722,120 T C +58 YES 0.0081 rs35923541 2 60,722,197 T — +58 Monomorphic 0.0000 rs35815093 2 60,722,208 G — +58 Failed Assay Design — rs147659683 2 60,722,219 G A +58 Failed Assay Design — rs6738440 2 60,722,241 A G +58 YES 0.2732 rs189178945 2 60,722,449 G A +58 Monomorphic 0.0000 rs140819321 2 60,722,465 G A +58 YES 0.0064 rs181895125 2 60,722,609 A G +58 Monomorphic 0.0000 rs144676401 2 60,722,634 C T +58 Monomorphic 0.0000 rs147910897 2 60,724,818 T C +55 YES 0.0132 rs34322220 2 60,724,831 T — +55 Monomorphic 0.0000 rs148529953 2 60,724,967 A G +55 YES 0.0140 rs188426060 2 60,724,989 T G +55 Failed Assay Design — rs191734859 2 60,724,994 A G +55 Failed Assay Design — rs45442493 2 60,725,043 G C +55 Monomorphic 0.0000 rs59444712 2 60,725,047 T C +55 Failed Assay Design — rs35173197 2 60,725,052 G — +55 Failed Assay Design — rs188151753 2 60,725,071 G A +55 Failed Assay Design — rs181041409 2 60,725,143 C A +55 Failed Assay Design — rs142174420 2 60,725,169 C A +55 Monomorphic 0.0000 rs187333125 2 60,725,342 C G +55 Monomorphic 0.0000 rs45566439 2 60,725,384 C T +55 Failed Assay Design — rs7606173 2 60,725,451 G C +55 YES 0.4235 rs190502487 2 60,725,499 C T +55 Failed Assay Design — rs151187913 2 60,725,714 G T +55 Monomorphic 0.0000 rs113798461 2 60,725,727 T C +55 Monomorphic 0.0000 rs181699714 2 60,726,054 G A +55 Failed Genotyping — SNPs falling within BCL11A DHSs +62, +58, or +55 and present in either dbSNP or the 1000 Genomes data for YRI, CEU and ASW reference populations. Genotyped SNPs are identified and MAF within the CSSCD listed. Genomic coordinates hg19.

TABLE 3 Additional markers found by Sanger re-sequencing Major Minor Marker CHR POS Allele Allele DHS Genotyped MAF ss711589103 2 60,717,561 T A +62 YES 0.00085 ss711589106 2 60,718,048 C G +62 Failed Assay Design — ss711589108 2 60,722,056 G A +58 YES 0.00424 ss711589109 2 60,722,355 C T +58 YES 0.00085 ss711589110 2 60,722,358 C T +58 Failed Assay Design — ss711589111 2 60,725,211 G T +55 YES 0.00509 ss711589113 2 60,725,564 C A +55 YES 0.00127 88 individuals from CSSCD with extreme HbF phenotype underwent Sanger re-sequencing of the three DHSs within BCL11A. Identified novel markers listed. Genotyped SNPs are identified and MAF within the CSSCD listed. Genomic coordinates hg19.

TABLE 4 Conditional analyses of four sentinel SNPs Conditional on Conditional on Conditional on Conditional on rs1427407 rs766432 rs11886868 rs4671393 Marker MAF β P β P β P β P β P rs1427407 0.245 0.659 4.56 × 10⁻²⁹ — — 0.656 3.38 × 10⁻⁶ 0.651  2.77 × 10⁻¹⁰ 0.666 1.86 × 10⁻⁶ rs766432 0.275 0.579 2.48 × 10⁻²⁴ 0.0036 0.979 — — 0.479 1.07 × 10⁻⁵ NA NA rs11886868 0.302 0.509 2.51 × 10⁻²¹ 0.0097 0.918 0.112 0.284 — — 0.123 0.234 rs4671393 0.274 0.576 4.41 × 10⁻²⁴ −0.0065 0.961 NA NA 0.466  1.7 × 10⁻⁵ — — Conditional analyses of four common sentinel SNPs previously associated with HbF levels{{44;20;19;36;37;515}}. All four were genotyped in 728 individuals from the CSSCD. It was not possible to calculate P for rs766432 when conditioning on rs4671393 (and vice versa) because these two markers are so strongly correlated (r² = 0.997). r² = 0.848 between rs1427407 and rs766432; r² = 0.709 between rs1427407 and rs11886868; r² = 0.850 between rs1427407 and rs4671393; r² = 0.761 between rs766432 and rs11886868; r² = 0.758 between rs11886868 and rs4671393.

TABLE 5 Rare and low-frequency variant analysis Conditional on Conditional on rs1427407 and Markers rs1427407 rs7606173 DHS (n) P P P +62 4 0.001488515 0.06092413 0.59352715 +58 6 0.065057555 0.03668287 0.07145516 +55 4 0.006806853 0.35021761 0.75880018 all 14 0.000631176 0.1503518 0.6908852 Rare and low-frequency variant analysis results (MAF < 5%). The analysis was performed using the set-based SKAT-O algorithm using the individual DHSs +62, +58, and +55 as three different sets. The bottom row “all” shows the results of the tests when the three regions were collapsed together.

TABLE 6 Emulsion fusion haplotyping PCR sequencing Likelihood ratio Donor no. G-G A-T G-T A-G G-G/A-Tuhase 1 19 22 4 2 1.63 × 10²⁹ 2 22 14 2 3 3.78 × 10²⁶ 3 25 23 9 10 4.69 × 10¹¹ Emulsion fusion PCR analysis of rs7569946-rs1427407 haplotype. Fusion PCR conducted in emulsion from three individual donors doubly heterozygous for rs7569946 and rs1427407, generating a fusion amplicon encompassing both SNPs. The fusion amplicon was cloned, and individual clones were Sanger sequenced. The number of clones of each genotype is listed. The likelihood ratio for the G-G/A-T as compared to G-T/A-G phase was calculated.

TABLE 7 Coordinates of fragments for reporter assays Distance from BCL11A hg19, chr2 TSS (kb) Reporter Name Start End Start End Length (bp) LacZ 52.0-64.4 60,716,189 60,728,612 64,444 52,021 12,423 56.8-64.4 60,716,189 60,723,870 64,444 56,763 7,681 52.0-57.6 60,722,992 60,728,612 57,641 52,021 5,620 +62 60,717,236 60,719,036 63,397 61,597 1,800 +58 60,722,006 60,723,058 58,627 57,575 1,052 +55 60,724,917 60,726,282 55,716 54,351 1,365 GFP +164 60,616,396 60,618,032 164,237 162,601 1,636 +156 60,623,536 60,624,989 157,097 155,644 1,453 +153 60,626,565 60,628,177 154,068 152,456 1,612 +62 60,717,236 60,719,036 63,397 61,597 1,800 +58 60,721,212 60,722,958 59,421 57,675 1,746 +55 60,724,780 60,726,471 55,853 54,162 1,691 +41 60,739,075 60,740,154 41,558 40,479 1,079 +32 60,748,003 60,749,009 32,630 31,624 1,006 −46 60,826,438 60,827,601 −45,805 −46,968 1,163 −52 60,831,589 60,833,556 −50,956 −52,923 1,967 Coordinates of the putative enhancer fragments cloned in the enhancer reporter assays. Chromosome 2 coordinates listed in hg19 as well as in reference to the BCL11A TSS.

TABLE 8 Oligonucleotide sequences. Name Sequence Assay mBcl11a-5′-F AAAGAGCTGTCCGAAGTCCA TALEN deletion PCR (SEQ ID NO: 7) mBcl11a-5′-R GGGCACTTCCTAGTCCCTCT TALEN deletion PCR (SEQ ID NO: 8) mBcl11a-dell-F TTTGAGCAGGAGGGAATTTG TALEN deletion PCR (SEQ ID NO: 9) mBcl11a-dell-R ATGTTGTGGTCCCTGTGGTT TALEN deletion PCR (SEQ ID NO: 10) mBcl11a-del2-F GCAAGGCAGGTACCAAACAT TALEN deletion PCR (SEQ ID NO: 11) mBcl11a-del2-R TAGAGATTCCAGGCCCCTTT TALEN deletion PCR (SEQ ID NO: 12) mBcl11a-3′-F AGCAAGGAAAGGTGAAGCAG TALEN deletion PCR (SEQ ID NO: 13) mBcl11a-3′-R CCCAATGTCTTCCGAACTGT TALEN deletion PCR (SEQ ID NO: 14) mBcl11a- AGGCTGGTCTTGGGATTTTT TALEN deletion PCR (SEQ ID NO: 15) upstreamTALEN-F mBcl11a- GCCTTTAACAAGGGTGTCCA TALEN deletion PCR (SEQ ID NO: 16) downstreamTALEN-R mBcl11a-5′probe-F CATAGACCTGGGTCCTGGAA 5′-probe for Southern blot (SEQ ID NO: 17) mBcl11a-5′probe-R TTGCAGAGTGACTCCTGTGG 5′-probe for Southern blot (SEQ ID NO: 18) hBCL11A-52.0-F CCAGCCATACCCAAAACAAA lacZ reporter cloning (SEQ ID NO: 19) hBCL11A-64.4-R CTTTCCCTCTTGCCACTCAG lacZ reporter cloning (SEQ ID NO: 20) hBCL11A-56.8-F GGCAGAGAAGGCACAGTGA lacZ reporter cloning (SEQ ID NO: 21) hBCL11A-57.6-R GGCTGTCCTGGCATGTAAGT lacZ reporter cloning (SEQ ID NO: 22) hBCL11A-63.4-F AACAGACCCATGTGCTAGGC lacZ/GFP reporter cloning (SEQ ID NO: 23) hBCL11A-61.6-R TGTGTGGACTGCCTTTTCTG lacZ/GFP reporter cloning (SEQ ID NO: 24) hBCL11A-58.6-F GGGAAAAGGGAGAGGAAAAA lacZ reporter cloning (SEQ ID NO: 25) hBCL11A-57.6-R CTCAGAAAAATGACAGCACCA lacZ reporter cloning (SEQ ID NO: 26) hBCL11A-55.7-F GGACTCAGTGGCCTCTTTTG lacZ reporter cloning (SEQ ID NO: 27) hBCL11A-54.4-R GAAGATAATGGCAGCCCAGA lacZ reporter cloning (SEQ ID NO: 28) hBCL11A-164.2-F TGTGTGGCCAACCTGTAAAA GFP reporter cloning (SEQ ID NO: 29) hBCL11A-162.6-R CTCGCTCTGTTTCCCAGTTC GFP reporter cloning (SEQ ID NO: 30) hBCL11A-157.1-F CTCTCCGACGACCTCTTTTG GFP reporter cloning (SEQ ID NO: 31) hBCL11A-155.6-R GTAGGGAAGGGGCTACTTGG GFP reporter cloning (SEQ ID NO: 32) hBCL11A-154.1-F AGAGCCAAACTCCGTCTCAA GFP reporter cloning (SEQ ID NO: 33) hBCL11A-152.5-R AAATACCACAGCCCAACAGC GFP reporter cloning (SEQ ID NO: 34) hBCL11A-59.4-F GAACAGAGACCACTACTGGCAAT GFP reporter cloning (SEQ ID NO: 35) hBCL11A-57.7-R GGGGAAGGGGTATTGAATTG GFP reporter cloning (SEQ ID NO: 36) hBCL11A-55.9-F CTTCCACTGGATGGCACTTT GFP reporter cloning (SEQ ID NO: 37) hBCL11A-54.2-R ACTTCAGCCTCCAGCACTGT GFP reporter cloning (SEQ ID NO: 38) hBCL11A-41.6-F CCTCCCAGCAATGTAGGTGT GFP reporter cloning (SEQ ID NO: 39) hBCL11A-40.5-R TGGTGTGGTCCACTGTGACT GFP reporter cloning (SEQ ID NO: 40) hBCL11A-32.6-F GCAAGCTTAGCCCCTTCTTT GFP reporter cloning (SEQ ID NO: 41) hBCL11A-31.6-R TGAGGCAGAGTCAGATGTGG GFP reporter cloning (SEQ ID NO: 42) hBCL11A-n45.8-F CCCCGCTCAGAGTAAGTGAG GFP reporter cloning (SEQ ID NO: 43) hBCL11A-n47.0-R GGAAACTGCCTATCCCATGA GFP reporter cloning (SEQ ID NO: 44) hBCL11A-n51.0-F CAACACCCCGATTTCAGACT GFP reporter cloning (SEQ ID NO: 45) hBCL11A-n52.9-R GAATGGTCCCGATCTCTTGA GFP reporter cloning (SEQ ID NO: 46) mGapdh-RT-F TGGTGAAGGTCGGTGTGAAC RT-qPCR (Gapdh) (SEQ ID NO: 47) mGapdh-RT-R CCATGTAGTTGAGGTCAATGAAGG RT-qPCR (Gapdh) (SEQ ID NO: 48) mBcl11a-RT-e1e2-F AACCCCAGCACTTAAGCAAA RT-qPCR (Bcl11a exon-1/2) (SEQ ID NO: 49) mBc111a-RT-e1e2-R ACAGGTGAGAAGGTCGTGGT RT-qPCR (Bcl11a exon-1/2) (SEQ ID NO: 50) mBc111a-RT-e2e3-F GCCCCAAACAGGAACACATA RT-qPCR (Bcl11a exon-2/3) (SEQ ID NO: 51) mBc111a-RT-e2e3-R GGGGCATATTCTGCACTCAT RT-qPCR (Bcl11a exon-2/3) (SEQ ID NO: 52) mBc111a-RT-e4e4-F ATGCGAGCTGTGCAACTATG RT-qPCR (Bcl11a exon-4/4,  (SEQ ID NO: 53) XLisoform) mBc111a-RT-e4e4-R GTAAACGTCCTTCCCCACCT RT-qPCR (Bcl11a exon-4/4,  (SEQ ID NO: 54) XLisoform) mBc111a-RT-e4e5-F CAGCTCAAAAGAGGGCAGAC RT-qPCR (Bcl11a exon-4/5,  (SEQ ID NO: 55) Lisoform) mBc111a-RT-e4e5-R GAGCTTCCATCCGAAAACTG RT-qPCR (Bcl11a exon-4/5,  (SEQ ID NO: 56) Lisoform) mHbby-RT-F TGGCCTGTGGAGTAAGGTCAA RT-qPCR (eY) (SEQ ID NO: 57) mHbby-RT-R GAAGCAGAGGACAAGTTCCCA RT-qPCR (eY) (SEQ ID NO: 58) mHbb-bh1-RT-F TGGACAACCTCAAGGAGACC RT-qPCR (bH1) (SEQ ID NO: 59) mHbb-bh1-RT-R ACCTCTGGGGTGAATTCCTT RT-qPCR (bH1) (SEQ ID NO: 60) mHbb-b1-RT-F TTTAACGATGGCCTGAATCACTT RT-qPCR (b1/b2) (SEQ ID NO: 61) mHbb-b1-RT-R CAGCACAATCACGATCATATTGC RT-qPCR (b1/b2) (SEQ ID NO: 62) lacZ-RT-F GCCAACATTGAGACACATGG RT-qPCR (lacZ) (SEQ ID NO: 63) lacZ-RT-R TGTCTCTCTGCACCATCCTG RT-qPCR (lacZ) (SEQ ID NO: 64) lacZ-F TTCAATGCTGTCAGGTGCTC PCR genotyping (lacZ) (SEQ ID NO: 65) lacZ-R GCCATGTGTCTCAATGTTGG PCR genotyping (lacZ) (SEQ ID NO: 66) rs7569946-F GTCTGCCCTCTTTTGAGCTG haplotyping fusion PCR (SEQ ID NO: 67) r57569946-R GACTCCAGACAATCGCCTTT haplotyping fusion PCR (SEQ ID NO: 68) r57569946-R-rc- AAAGGCGATTGTCTGGAGTCAACCTT bridging primer, haplotyping  (SEQ ID NO: 69) fusion r51427407-F CTTAGCACCCACAAAC PCR (SEQ ID NO: 70) r51427407-R CATGTTACTGCAACTTGCTTTTT haplotyping fusion PCR (SEQ ID NO: 71) r57569946-nested-F AGATCCCTCCGTCCAGCTC haplotyping fusion PCR (SEQ ID NO: 72) r51427407-nested-R TGAAAGTTCAAGTAGATATCAGAAGG haplotyping fusion PCR (SEQ ID NO: 73) 3C-hBCL11A-150.6-F AGCAAACCACACAGACTGAAGA 3C (SEQ ID NO: 74) 3C-hBCL11A-140.9-F CCAGAGCCATTTACGTCACA 3C (SEQ ID NO: 75) 3C-hBCL11A-114.1-F CAGAAGGGAATAAGGTACTCTGGA 3C (SEQ ID NO: 76) 3C-hBCL11A-111.5-F GTTTGGGCCTCAAGGTCTTT 3C (SEQ ID NO: 77) 3C-hBCL11A-109.1-F GAGGTTGGGAGTAAGCATTCTG 3C (SEQ ID NO: 78) 3C-hBCL11A-100.7-F ACGCATCAGAATGCCCATAG 3C (SEQ ID NO: 79) 3C-hBCL11A-92.3-F TTTTGAAAGAAAACGCTGACA 3C (SEQ ID NO: 80) 3C-hBCL11A-80.2-F TTCCAGCTGGTTAAATTTAGGG 3C (SEQ ID NO: 81) 3C-hBCL11A-77.2-F AGAAGGGGCCAGAAGAACAG 3C (SEQ ID NO: 82) 3C-hBCL11A-72.5-F CCTTCTTTTTCTTTCTTGGTTGC 3C (SEQ ID NO: 83) 3C-hBCL11A-66.8-F CCCTGCGTGCCATTAAAATA 3C (SEQ ID NO: 84) 3C-hBCL11A-61.2-F AAAGGCCTTGGGAAGAAAGA 3C (SEQ ID NO: 85) 3C-hBCL11A-59.1-F GCAAGTCAGTTGGGAACACA 3C (SEQ ID NO: 86) 3C-hBCL11A-57.1-F GGACTCAGTGGCCTCTTTTG 3C (SEQ ID NO: 87) 3C-hBCL11A-52.2-F CTGTCTCTGTCTCCCCCAAG 3C (SEQ ID NO: 88) 3C-hBCL11A-47-F CCAATGCTCCTGTAACAAAGG 3C (SEQ ID NO: 89) 3C-hBCL11A-43.5-F AATGCAGTAGGCAAAGAAGCA 3C (SEQ ID NO: 90) 3C-hBCL11A-38.6-F GAAATTTGGAAGGCCACAGA 3C (SEQ ID NO: 91) 3C-hBCL11A-29.3-F GCTTGCAACAATTAAAAGATGG 3C (SEQ ID NO: 92) 3C-hBCL11A-27.1-F GGTGACAAGGGAGAACCACT 3C (SEQ ID NO: 93) 3C-hBCL11A-20.9-F TGATTTCCTTGCAGCCTTTT 3C (SEQ ID NO: 94) 3C-hBCL11A-8.6-F CACACCCACAGCAACAAATG 3C (SEQ ID NO: 95) 3C-hBCL11Apromoter-R TGCAGAGATCCCCCAAAGTA 3C (SEQ ID NO: 96) 3C-hBCL11A-n8.3-F CTCAGGGAGCAAGGGAAATA 3C (SEQ ID NO: 97) 3C-hBCL11A-n12.6-F CCCTCCCAACAGGGATTTAT 3C (SEQ ID NO: 98) 3C-hBCL11A-n19.5-F CAAAATTGAACACCTATGGTCTGA 3C (SEQ ID NO: 99) 3C-hBCL11A-n29.8-F AGGAAGACTTTGGCCTCCAT 3C (SEQ ID NO: 100) 3C-hBCL11A-n34.6-F TTCCAAACAATTATACACCAACAAA 3C (SEQ ID NO: 101) 3C-hBCL11A-n54-F TTTCATGGGGAATAGCCAAC 3C (SEQ ID NO: 102) 3C-hBCL11A-n78.2-F CCCTACTTGTTATTTGCTTCTGC 3C (SEQ ID NO: 103) 3C-hBCL11A-n104.4-F AGCTGAAGTTTCAGGGACCA 3C (SEQ ID NO: 104) 3C-LCR-HS1-F CCACACCTGCCTTCCTTAGA 3C (SEQ ID NO: 105) 3C-LCR-H53-F TGCATATGATGGGGTAGCAG 3C (SEQ ID NO: 106) ChlP-hBCL11A-68.7-F AAGAGAAGGGGGAATTTGGA ChlP-qPCR (SEQ ID NO: 107) ChlP-hBCL11A-68.7-R TGGTGATAAGGGCAGGAAAC ChlP-qPCR (SEQ ID NO: 108) ChlP-hBCL11A-65.5-F AGGAAGCTGCAGAAAGGTGA ChlP-qPCR (SEQ ID NO: 109) ChlP-hBCL11A-65.5-R TGCTTCCCCAGGTTTAGATG ChlP-qPCR (SEQ ID NO: 110) ChlP-hBCL11A-64.7-F CCACTGCTACCCAAAACGAT ChlP-qPCR (SEQ ID NO: 111) ChlP-hBCL11A-64.7-R CAAGAGCGAAACTCCACCTC ChlP-qPCR (SEQ ID NO: 112) ChlP-hBCL11A-63.9-F ACTGTGTGCCAAGTGACCAG ChlP-qPCR (SEQ ID NO: 113) ChlP-hBCL11A-63.9-R CAGCTTCCTTCAGGTGCTTC ChlP-qPCR (SEQ ID NO: 114) ChlP-hBCL11A-63.1-F CATGCTGCCTTTGTCTTCTG ChlP-qPCR (SEQ ID NO: 115) ChlP-hBCL11A-63.1-R TGTGGAGCTCTGGAATGATG ChlP-qPCR (SEQ ID NO: 116) ChlP-hBCL11A-63.0-F GAGCTCCACAATCCAACTCC ChlP-qPCR (SEQ ID NO: 117) ChlP-hBCL11A-63.0-R CCAGGAAGGAAATGAGAACG ChlP-qPCR (SEQ ID NO: 118) ChlP-hBCL11A-62.5-F ACCCACAAACATTTCCCTTCT ChlP-qPCR (SEQ ID NO: 119) ChlP-hBCL11A-62.5-R TTTGCTCTTCTCCAGGGTGT ChlP-qPCR (SEQ ID NO: 120) ChlP-hBCL11A-62.4-F TTTAAACAGCCACCCCACAC ChlP-qPCR (SEQ ID NO: 121) ChlP-hBCL11A-62.4-R ACCACGTAGTTGGGCTTCAC ChlP-qPCR (SEQ ID NO: 122) ChlP-hBCL11A-62.2-F TTTCAACCATGGTCATCTGC ChlP-qPCR (SEQ ID NO: 123) ChlP-hBCL11A-62.2-R CCCTCTGGCATCAAAATGAG ChlP-qPCR (SEQ ID NO: 124) ChlP-hBCL11A-61.8-F GAACCTGGGAGGCAGAAGAT ChlP-qPCR (SEQ ID NO: 125) ChlP-hBCL11A-61.8-R TTTTTGGTGAGACGGAGATTT ChlP-qPCR (SEQ ID NO: 126) ChlP-hBCL11A-61.7-F CCGGGCAACAAGAGTAAATC ChlP-qPCR (SEQ ID NO: 127) ChlP-hBCL11A-61.7-R ATGCCTAGGGTGTTTTGACG ChlP-qPCR (SEQ ID NO: 128) ChlP-hBCL11A-61.5-F CTCCGTGTTGAGAGCCAAGT ChlP-qPCR (SEQ ID NO: 129) ChlP-hBCL11A-61.5-R TGTGTGGACTGCCTTTTCTG ChlP-qPCR (SEQ ID NO: 130) ChlP-hBCL11A-61.3-F CAGAAAAGGCAGTCCACACA ChlP-qPCR (SEQ ID NO: 131) ChlP-hBCL11A-61.3-R CCTCTCCAGATTCCCTCTCA ChlP-qPCR (SEQ ID NO: 132) ChlP-hBCL11A-61.0-F AGCGAGACCCTGTCTCAAAA ChlP-qPCR (SEQ ID NO: 133) ChlP-hBCL11A-61.0-R TCCAGCAGGCTTCAAAAAGT ChlP-qPCR (SEQ ID NO: 134) ChlP-hBCL11A-60.8-F GGTGGATAACCCCATCTCAG ChlP-qPCR (SEQ ID NO: 135) ChlP-hBCL11A-60.8-R GGAAATGAGAATGCCCTTTG ChlP-qPCR (SEQ ID NO: 136) ChlP-hBCL11A-60.5-F CAGTCTAGAAAGCCCCCTCA ChlP-qPCR (SEQ ID NO: 137) ChlP-hBCL11A-60.5-R GTGGGGGTTCAGTGGTTAGA ChlP-qPCR (SEQ ID NO: 138) ChlP-hBCL11A-60.3-F TCCATGGTGTGGAGTGTGTT ChlP-qPCR (SEQ ID NO: 139) ChlP-hBCL11A-60.3-R ACCCACATGGCAACCAATAG ChlP-qPCR (SEQ ID NO: 140) ChlP-hBCL11A-60.0-F CCATTCCCTGGAGAGTTCAA ChlP-qPCR (SEQ ID NO: 141) ChlP-hBCL11A-60.0-R GGGGTCTCTTCCCATCATTT ChlP-qPCR (SEQ ID NO: 142) ChlP-hBCL11A-59.9-F ATGGGAAGAGACCCCAAAAC ChlP-qPCR (SEQ ID NO: 143) ChlP-hBCL11A-59.9-R GGACTCCGAACACCACACTT ChlP-qPCR (SEQ ID NO: 144) ChlP-hBCL11A-59.5-F GGGATCAGAGGTGAACAGGA ChlP-qPCR (SEQ ID NO: 145) ChlP-hBCL11A-59.5-R TTTAATCAGCTTCCGCCACT ChlP-qPCR (SEQ ID NO: 146) ChlP-hBCL11A-59.0-F TGGGGAGAGAAGAGTGGAAA ChlP-qPCR (SEQ ID NO: 147) ChlP-hBCL11A-59.0-R TTGCCAATTGGAGATTAGGG ChlP-qPCR (SEQ ID NO: 148) ChlP-hBCL11A-58.7-F TGCTCCGAGCTTGTGAACTA ChlP-qPCR (SEQ ID NO: 149) ChlP-hBCL11A-58.7-R GGGAAAGGGCCTGATAACTT ChlP-qPCR (SEQ ID NO: 150) ChlP-hBCL11A-58.3-F GAGAGTGCAGACAGGGGAAG ChlP-qPCR (SEQ ID NO: 151) ChlP-hBCL11A-58.3-R CCTCTTTCGGAAGGCTCTCT ChlP-qPCR (SEQ ID NO: 152) ChlP-hBCL11A-58.0-F TGGACTTTGCACTGGAATCA ChlP-qPCR (SEQ ID NO: 153) ChlP-hBCL11A-58.0-R GATGGCTGAAAAGCGATACA ChlP-qPCR (SEQ ID NO: 154) ChlP-hBCL11A-57.3-F GGGGAGATGATTGAAAGCAA ChlP-qPCR (SEQ ID NO: 155) ChlP-hBCL11A-57.3-R AGAACTTTCCCGGTTCTGGT ChlP-qPCR (SEQ ID NO: 156) ChlP-hBCL11A-57.0-F GCTCTGGACACACAGCAAAA ChlP-qPCR (SEQ ID NO: 157) ChlP-hBCL11A-57.0-R TCAAATCCTTGCCTTGAACC ChlP-qPCR (SEQ ID NO: 158) ChlP-hBCL11A-56.6-F CCTCAAATCTCCCTCACTGG ChlP-qPCR (SEQ ID NO: 159) ChlP-hBCL11A-56.6-R GGGAAATGGGTCCTGCTTTA ChlP-qPCR (SEQ ID NO: 160) ChlP-hBCL11A-56.3-F AGGGAGTACACCGCAGACAC ChlP-qPCR (SEQ ID NO: 161) ChlP-hBCL11A-56.3-R AAGGAAGGCTGCAAGGAAAT ChlP-qPCR (SEQ ID NO: 162) ChlP-hBCL11A-55.9-F GACTTAAACTGCCGCTCCTG ChlP-qPCR (SEQ ID NO: 163) ChlP-hBCL11A-55.9-R TGACTGGTAAGAGCCGATTG ChlP-qPCR (SEQ ID NO: 164) ChlP-hBCL11A-55.3-F GCTGGGGTGAGTCAAAAGTC ChlP-qPCR (SEQ ID NO: 165) ChlP-hBCL11A-55.3-R GGTCACCTTAAGGAGCCACA ChlP-qPCR (SEQ ID NO: 166) ChlP-hBCL11A-54.8-F GCACCTGCATTTGTTTTTCA ChlP-qPCR (SEQ ID NO: 167) ChlP-hBCL11A-54.8-R GGGTCAGATCACCTCTGCTC ChlP-qPCR (SEQ ID NO: 168) ChlP-hBCL11A-54.4-F AGGCATCCAAAGGGAAGAAT ChlP-qPCR (SEQ ID NO: 169) ChlP-hBCL11A-54.4-R GAAGATAATGGCAGCCCAGA ChlP-qPCR (SEQ ID NO: 170) ChlP-hBCL11A-54.0-F TGGGAAAGGTTGCACATTCT ChlP-qPCR (SEQ ID NO: 171) ChlP-hBCL11A-54.0-R GGGCCTCAGGCTCTTTATCT ChlP-qPCR (SEQ ID NO: 172) ChlP-hBCL11A-53.4-F CCACTGCCAGGCTGTTTACT ChlP-qPCR (SEQ ID NO: 173) ChlP-hBCL11A-53.4-R GACCGAAAGGAGGAGAGGAG ChlP-qPCR (SEQ ID NO: 174) ChlP-hBCL11A-53.1-F CAGTTCCCCCATTATGCACT ChlP-qPCR (SEQ ID NO: 175) ChlP-hBCL11A-53.1-R CCCTTCTCTGAAGGCACATC ChlP-qPCR (SEQ ID NO: 176) ChlP-hBCL11A-52.7-F TTCAAGCCTTGGTGGATAGG ChlP-qPCR (SEQ ID NO: 177) ChlP-hBCL11A-52.7-R GCCAGGAAATTGGTGGTAGA ChlP-qPCR (SEQ ID NO: 178) ChlP-hBCL11A-52.3-F TGCCCACATGAGACATCTTT ChlP-qPCR (SEQ ID NO: 179) ChlP-hBCL11A-52.3-R AAATTGGCTGCCATTGAATC ChlP-qPCR (SEQ ID NO: 180) ChlP-hBCL11A-51.3-F CCACCAGAAGTCCTGGAAAA ChlP-qPCR (SEQ ID NO: 181) ChlP-hBCL11A-51.3-R TTGGAGGGACCTGATCTCTG ChlP-qPCR (SEQ ID NO: 182) ChlP-hBCL11A-50.2-F CCAAGATGGAGAAGCCACAT ChlP-qPCR (SEQ ID NO: 183) ChlP-hBCL11A-50.2-R TCTGTCTTGGGTCTCCTGGT ChlP-qPCR (SEQ ID NO: 184) ChlP-hBCL11A-49.8-F GAGAAGCCCTCAGCAAACAC ChlP-qPCR (SEQ ID NO: 185) ChlP-hBCL11A-49.8-R GGTTGCATCTTGGCTCCTAA ChlP-qPCR (SEQ ID NO: 186) ChlP-hBCL11A-49.5-F GAAATGCAGGAAAGGAACGA ChlP-qPCR (SEQ ID NO: 187) ChlP-hBCL11A-49.5-R TCTAGCAGATGGGGTTTTGG ChlP-qPCR (SEQ ID NO: 188) ChlP-h0ct4-prom-F AGTCTGGGCAACAAAGTGAGA ChlP-qPCR (SEQ ID NO: 189) ChlP-h0ct4-prom-R AGAAACTGAGGAGAAGGATG ChlP-qPCR (SEQ ID NO: 190) ChlP-hHS3-F ATAGACCATGAGTAGAGGGCAGAC ChlP-qPCR (SEQ ID NO: 191) ChlP-hHS3-R TGATCCTGAAAACATAGGAGTCAA ChlP-qPCR (SEQ ID NO: 192) ChlP-hHS-40-F CAGATAACTGGGCCAACCAT ChlP-qPCR (SEQ ID NO: 193) ChlP-hHS-40-R ATTCACCCCTTTCCCTTGTC ChlP-qPCR (SEQ ID NO: 194) ChlP-hGAPDH-F CGTAGCTCAGGCCTCAAGAC ChlP-qPCR (SEQ ID NO: 195) ChlP-hGAPDH-R CGAACAGGAGGAGCAGAGAG ChlP-qPCR (SEQ ID NO: 196) Oligonucleotides used in indicated experiments. 

What is claimed:
 1. A human hematopoietic progenitor cell comprising at least one genetic modification within chromosome 2 between positions 60,716,189 and 60,728,612 (according to UCSC Genome Browser hg 1.9 human genome assembly), wherein the human hematopoietic progenitor cell comprises i) a vector comprising a regulatory element operably linked to a coding sequence of a DNA-targeting endonuclease comprising a TAL DNA binding domain or ii) an RNA encoding a DNA-targeting endonuclease comprising a TAL DNA binding domain; wherein the DNA-targeting endonuclease binds to and cleaves the genomic DNA of the cell within the chromosome 2 between positions 60,716,189 and 60,728,612 to generate the at least one genetic modification; wherein the at least one genetic modification is an insertion or a deletion that disrupts DNAse hypersensitive sites +62, +58, or +55 therein; and wherein the at least one genetic modification reduces BCL11A mRNA and protein expression in the human hematopoietic progenitor cell or its progeny.
 2. The human hematopoietic progenitor cell of claim 1, wherein the at least one genetic modification is the insertion.
 3. The human hematopoietic progenitor cell of claim 1, wherein the at least one genetic modification is the deletion.
 4. The human hematopoietic progenitor cell of claim 3, wherein the deletion removes the entire region between the chromosome 2 location 60,716,189 and 60,728,612 or removes one or more DHSs in the region.
 5. The human hematopoietic progenitor cell of claim 4, wherein the deletion removes the entire region between the chromosome 2 location 60,716,189 and 60,728,612.
 6. The human hematopoietic progenitor cell of claim 4, wherein the deletion removes the entire region between chromosome 2 location 60,717,492 and 60,718,860.
 7. The human hematopoietic progenitor cell of claim 4, wherein the deletion removes the entire region between chromosome 2 location 60,721,411 and 60,722,674.
 8. The human hematopoietic progenitor cell of claim 4, wherein the deletion removes the entire region between chromosome 2 location 60,724,802 and 60,726,084.
 9. The human hematopoietic progenitor cell of claim 4, wherein the deletion disrupts the DHS +62.
 10. The human hematopoietic progenitor cell of claim 4, wherein the deletion disrupts the DHS +58.
 11. The human hematopoietic progenitor cell of claim 4, wherein the deletion disrupts the DHS +55.
 12. The human hematopoietic progenitor cell of claim 1, wherein the human hematopoietic progenitor cell is modified ex vivo.
 13. The human hematopoietic progenitor cell of claim 1, wherein the cell is an erythroid lineage cell.
 14. A pharmaceutical composition comprising a pharmaceutically acceptable carrier and a human hematopoietic progenitor cell comprising at least one genetic modification within chromosome 2 between positions 60,716,18960,728,612 (according to UCSC Genome Browser hg 1.9 human genome assembly), wherein the at least one genetic modification is an insertion or a deletion that disrupts DNAse hypersensitive sites +62, +58, or +55 therein, and wherein the at least one genetic modification reduces BCL11A mRNA and protein expression in the human hematopoietic progenitor cell or its progeny. 